PHYLUM ARTHROPODA · ARACHNIDA 2 4 None Simple Have chelicerae CRUSTACEA 2 5 2 pairs Compound...

PHYLUM ARTHROPODAGrade and Topic: Biology Grade 10, Period IV (Arthropods and Biological Control of Pests)

Table of Contents• Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

• Characteristics of Arthropods . . . . . . . . . . . . . . 2

• Classes of Arthropods . . . . . . . . . . . . . . . . . . . . 3

• Gaseous Exchange . . . . . . . . . . . . . . . . . . . . . . . 4

• Moulting and Metamorphosis . . . . . . . . . . . . . 4

• PRACTICALS (SET 1). . . . . . . . . . . . . . . . . . . . . . 5 (Questions) and 7 (Solutions)

• PAST WASSCE QUESTIONS (SET 1) . . . . . . . . . . 6 (Questions) and 8 (Solutions)

Common Arthropods • Bee . . . . . . . . 10 • Grasshopper . . . . . 12 • Spider . . . . 14 • Butterfly . . . . 11 • Housefly . . . . . . . . 13 • Termite . . . . 15 • Caterpillar . . . 11 • Maggot . . . . . . . . . 13 • Tick . . . . . . . 15 • Cockroach . . . 12 • Mosquito larva . . . 14 • Weevil . . . . . 16

• PRACTICALS (SET 2) . . . . . . . . . . . . . . . . . . . . . . 17 (Questions) and 22 (Solutions)

• ALTERNATIVE TO PRACTICAL QUESTIONS . . . . 19 (Questions) and 26 (Solutions)

• PAST WASSCE MULTIPLE CHOICE (SET 2) . . . . . 21 (Questions) and 30 (Solutions)

Looking for more notes? Go to handsonliberia.wordpress.com for additional notes on practicals in chemistry, biology, and physics.

*Please email [email protected] if you have questions or comments about these notes. Please also send an email to this address if you find any errors that need to be corrected.

-1-

http://handsonliberia.wordpress.com/

mailto:[email protected]

IntroductionArthropods are animals belonging to Phylum Arthropoda. The arthropods are the largest group of animals, and they live almost everywhere. There are arthropods in your house. There are arthropods in forests, lakes, and deep in the ocean. There are even arthropods living in the ice of Antarctica.

Grasshoppers, spiders, and crabs are all arthropods. Is a mosquito buzzing in your ear? You are hearing an arthropod. Do spiders live in the corners of your house? You are sharing a home with arthropods. Are you eating lobster soup for lunch? Then you are enjoying a sweet meal of arthropods.

Some examples of arthropods

The word arthopod means “jointed foot”. Look at the pictures of arthropods above. Their legs can bend, just like human beings can bend their legs at the knees. The parts of the leg that can bend are called joints. One special characteristic of arthropods is that they have jointed legs.

Characteristics of ArthropodsAll arthropods share four characteristics:

(1) Paired, jointed appendages (3) A segmented body(2) An exoskeleton made of chitin (4) Bilateral symmetry

The diagram below explains each characteristic. You should memorize the characteristics of arthropods. The WASSCE often asks about them.

Classes of ArthropodsThere are five classes of arthropods on the WASSCE. They are: (1) Insecta (2) Arachnida (3) Crustacea (4) Chilopoda (5) Diplopoda

You should learn the characteristics of each of these groups. See the next page for more details.

-2-

CLASSES OF ARTHROPODSClass Insecta

Grasshopper, butterfly, housefly, cockroach, etc.

• 3 body divisions (head, thorax, abdomen)• 3 pairs of legs• Compound eyes• 1 pair of antennae• Sometimes have 1 or 2 pairs of wings

Class ArachnidaSpider, scorpion, tick, etc.

• 2 body divisions (cephalothorax and abdomen)• 4 pairs of legs• Simple eyes • 1 pair of chelicerae*

*Chelicerae are sharp, pointed mouthparts that are used tograsp prey and inject it with poison

Class ChilopodaCentipede

• 1 pair of legs on each body segment• 1 pair of antennae• 1 pair of poisonous claws• Body is flat (dorsoventrally flattened)• Has a clearly defined head plus a large

number of body segments

Class DiplopodaMillipede

• 2 pairs of legs on each body segment• 1 pair of antennae• Body is cylindrical• Has a clearly defined head plus a large

number of body segments

Class CrustaceaCrab, lobster, prawn, crayfish, etc*

• 2 body divisions (cephalothorax and abdomen) • 2 pairs of antennae• 5 pairs of walking legs • Thick, hard exoskeleton• 1 pair of compound eyes

*In Liberia, we often use the word “crawfish”. But the standard spelling in biology is crayfish.

The table below summarizes the main characteristics of each class of arthropods.

Body divisions Pairs of legs Antennae Type of eyes Other

INSECTA 3 3 1 pair Compound Sometimes have wings

ARACHNIDA 2 4 None Simple Have chelicerae

CRUSTACEA 2 5 2 pairs Compound Thick, hard exoskeleton

CHILOPODA Many 1 per segment 1 pair May be simple orcompound

Poisonous claws and aflattened body

DIPLOPODA Many 2 per segment 1 pair May be simple orcompound

Cylindrical body

-3-

Additional Characteristics of ArthropodsGaseous ExchangeArthropods have many systems for bringing oxygen into their bodies and excreting carbon dioxide. These include:

1) Spiracles and tracheae – Spiracles are small holes in the exoskeleton that allow air to enter. They are connected to tubes called tracheae, which carry the air throughout the body. Insects, centipedes, and millipedes have spiracles and tracheae.

2) Book lungs – Book lungs are a simple type of lung. They are called book lungs because they have folded tissue that resembles the pages of a book. Arachnids such as spiders have book lungs.

3) Gills – Crustaceans use gills to breathe. Gills are different from spiracles and book lungs because they remove oxygen from water, while spiracles and book lungs remove oxygen from air.

GASEOUS EXCHANGE SYSTEMS IN ARTHROPODS

Spiracles and tracheae Book Lungs Gills

Insecta, Diplopoda, Chilopoda Arachnida Crustacea

MoultingMoulting is when an arthropod sheds its exoskeleton. The exoskeleton cannot change in size, so arthropods must moult in order to grow larger. They usually grow very fast after moulting, then they quickly grow a new exoskeleton over their bodies. Moulting is also called ecdysis.

MetamorphosisMetamorphosis is the change in body shape and structure as an organism develops from a juvenile into an adult. Insects develop through metamorphosis. Complete metamorphosis has four stages of development (egg, larva, pupa, and adult). Incomplete metamorphosis has only three stages of development (egg, larva, and adult). In incomplete metamorphosis, the larva is called a nymph.

Metamorphosis in InsectsSome insects develop by incomplete metamorphosis, while others have complete metamorphosis. In incomplete metamorphosis, the larva resembles the adult. In complete metamorphosis, the larva has a very different body shape and structure from the adult. It must become a pupa to develop into an adult.

Cockroaches are an example of incomplete metamorphosis. They have only three stages of development – egg, larva, and adult. The larva is called a nymph. It looks like an adult cockroach, but it is smaller and lacks wings. It does not become a pupa. Rather, it simply grows larger and develops directly into an adult.

Butterflies are an example of complete metamorphosis. They have four stages of development—egg, larva, pupa, and adult. The larva is called a caterpillar. It is long and thin, with many legs and no wings. The caterpillar does not develop directly into an adult. Instead, it becomes a pupa. The pupa protects thecaterpillar while it grows and changes. After some time, an adult butterfly emerges from the pupa.

-4-

Arthropods Practical #1 – Preparation Instructions

These instructions are for the TEACHER ONLY. Do not give this information to your students!1) Gather the following specimens:

A – Grasshopper B – Spider C – Crab or crayfish D – Snail E – Millipede

*All specimens should either be dead or be kept in jars with secure tops that prevent escape.

2) Place each specimen in a jar or on a plate. Label it with the letter given above. Do not write the name of the specimen. Do not tell the students the names of the specimens.

Arthropods Practical #1Observe each specimen carefully, then answer the questions that follow.

a) Identify each specimen without giving reasonsb) (i) List two observable similarities between specimens A and B. (ii) List three observable differences between specimens A and Bc) List two observable differences between specimens C and E.d) Which of the specimens does not belong to Phylum Arthropoda? Explain your reasoning.e) State the class of specimens A, B, and C. In each case, give two reasons for your choice.f) Draw a labeled diagram of the lateral view of specimen A. In your diagram, you should label

the following: leg, antenna, thorax, head, abdomen, wing, compound eye.

- Solutions to questions are on the last pages of the notes (page 7 and 8) -



A – Cockroach B – Housefly C – Spider D – Termite


2) Place each specimen in a jar or on a plate. Label it with the letter given above. Do not write the name of the specimen. Do not tell the students the names of the specimens.


a) Identify each specimen without giving reasons.b) What is the phylum of the specimens? Give two reasons for your answer.c) Name three specimens that belong to class Insecta.d) Name one specimen that does not belong to class Insecta. Write its class and give two reasons

for your answer.e) List three observable differences between specimens A and B.f) Draw a labeled diagram of the dorsal view of specimen C. Label the following: abdomen,

cephalothorax, leg, eyes, chelicerae.

- Solutions to questions are on the last pages of the notes (page 7 and 8) -

-5-

Test Your Knowledge: Arthropod Questions from Past WASSCE Tests - Solutions are on the next page -

1) Which of the following is a unique characteristic of arachnids?A. Segmented body B. 3 pairs of walking legs C. 4 pairs of walking legs D. Compound eyes

2) Which of the following characteristics is not true for all insects?A. Jointed appendages B. A pair of antennae C. A pair of wings D. Three pairs of walking legs

3) Which of the following arthropods possess two pairs of antennae?A. Cockroach B. Crayfish C. Millipede D. Spider

4) The cockroach and the butterfly are placed in the same class because both of them haveA. Exoskeleton B. Jointed appendages C. Segmented bodies D. Three body divisions

5) Which of the following structures are associated with respiration in insects?A. Air sac B. Spiracle C. Lung D. Alveolus E. Gill

6) The process in which insects undergo conspicuous changes in form and appearance during development is known as

A. Ecdysis B. Metamorphosis C. Aestivation D. Migration E. Hibernation

7) Which of the following stages is not present in incomplete metamorphosis?A. Imago B. Larva C. Nymph D. Pupa

8) The arthropod in the diagram is not an insect because itA. Has a big head which is almost equal to the thoraxB. Has eight legs and no wings C. Does not have visible eyes on its headD. Has a head, thorax, and abdomen

9) The structures in insects that serve familiar functions as the stomata in plants are theA. Tracheoles B. Spiracles C. Tracheae D. Trochanter

10) (a) State four characteristics of the phylum Arthropoda.(b) (i) Name the five different classes of this phylum.

(ii) Give one example each of the classes mentioned in (i) above.

11) List three structural features of each of the following classes.(a) Insecta (b) Crustacea (c) Arachnida

12) The diagram below shows organisms belonging to the phylum Arthropoda.

State which of the drawings shows: (a) an arachnid (b) an insect (c) a crustacean.In each case, give two reasons for your choice.

-6-

Solutions to Arthropod Questions from Past WASSCE Tests1) C. “Segmented bodies” is incorrect because all arthropods have segmented bodies, so this characteristic is

not unique to arachnids. “3 pairs of walking legs” applies to insects, not arachnids. “Compound eyes” is incorrect because these eyes are actually found in insects and crustaceans rather than arachnids.

2) C. Only some insects have wings, but all insects have 3 pairs of walking legs, jointed appendages, and a pair of antennae.

3) B. Crustaceans have two pairs of antennae, and a crayfish is an example of a crustacean.4) D. Cockroaches and butterflies belong to class Insecta, so the answer will be a characteristic of insects.

Answers A, B, and C are wrong because they are characteristics of all arthropods, but they are not unique to class Insecta. However, three body divisions is a unique characteristic of insects.

5) B. Insects use spiracles and tracheae to breathe.6) B. Metamorphosis refers to the change in body shape and structure as insects develop.7) D. Incomplete metamorphosis does not involve a pupa. It has only three stages: the egg, the larva (nymph),

and the adult (imago).8) B. The arthropod in the picture is an arachnid. Insects have six legs and often have wings, while arachnids

have eight legs and no wings.

9) B. Spiracles allow air to enter and exit the body of an insect, just as stomata allow air to enter and exit a leaf.10) a) Characteristics of phlyum Arthropoda: • Paired, jointed appendages • Bilateral symmetry

• Exoskeleton made of chitin • Segmented body

b) (i) Five classes of phylum Arthropoda: Insecta, Arachnida, Crustacea, Diplopoda, Chilopoda (ii) Examples of each class of arthropods (only one example required for each class):

Insecta – Cockroach/fly/butterfly/mosquito/grasshopper/weevil/termite/ant/beeArachnida – Spider/scorpion/tick/miteCrustacea – Crab/lobster/crayfish/prawnChilopoda – CentipedeDiplopoda – Millipede

11) a) Class Insecta (any 3): • 3 pairs of legs • 1 pair of compound eyes • 1 or 2 pairs of wings • 1 pair of antennae

• 3 body divisions (head, thorax, and abdomen)

b) Class Crustacea (any 3): • Thick, hard exoskeleton • 2 pairs of antennae • 5 pairs of walking legs • 1 pair of compound eyes • 2 body divisions (cephalothorax and abdomen)

c) Class Arachnida (any 3): • 1 pair of simple eyes • 1 pair of chelicerae • 4 pairs of legs • 2 body divisions (cephalothorax and abdomen)

12) a) Drawing E is an arachnid. Any two of the following reasons: • It has four pairs of legs • It has two body divisions • It has chelicerae “It has simple eyes” is incorrect because the eyes are not clearly visible in the drawing.

b) Drawing H is an insect. Any two of the following reasons: • It has three pairs of legs • It has three body divisions • It has one pair of antennae

Answers involving wings or compound eyes are incorrect because the wings and eyes are not present in the drawing.

c) Specimen G is a crustacean. Any two of the following reasons: • It has five pairs of legs • It has two body divisions • It has one pair of compound eyes • It has a thick, hard exoskeleton

“It has two pairs of antennae” is wrong because only one pair is visible in the picture.

-7-

Solutions to Arthropod PracticalsArthropods Practical #1a) A – Grasshopper B – Spider C – Crab (or crayfish) D – Snail E – Millipedeb) (i) Any two of the following:

• Both have jointed legs • Both have bilateral symmetry• Both have segmented bodies • Both have an exoskeleton (“chitinous exoskeleton” is • Both have eyes incorrect because the chitin cannot be observed with the eyes)

Accept any other reasonable similarity that can be observed with the eyes.

(ii) Any three of the following:

Specimen A (Grasshopper) Specimen B (Spider)

Has three pairs of legs Has four pairs of legs

Has three body divisions (head, thorax, and abdomen)

Has two body divisions (cephalothorax and abdomen)

Has wings Does not have wings

Has one pair of antennae Does not have antennae

Does not have chelicerae Has chelicerae

Legs do not have hairs Legs have hairs (if the specimen is a spider withhairs)

Accept any other reasonable difference that can be observed with the eyes.

c) Any two of the following:

Specimen C (Crab or Crayfish) Specimen E (Millipede)

Has five pairs of legs (including the claws) Has a very large number of legs

Has two pairs of antennae Has one pair of antennae

Has claws Does not have claws

Has a hard outer shell (carapace) Does not have a hard outer shell (carapace)

Has eyes on stems that protrude from the body Does not have eyes on protruding stems

Accept any other reasonable difference that can be observed with the eyes.

d) Specimen D (Snail) does not belong to Phylum Arthropoda because it does not have jointed limbs or a segmented body. It also does not have an exoskeleton (it has a shell, but this is not the same as an exoskeleton).

e) Specimen A (Grasshopper) belongs to Class Insecta. Any two of the following reasons:• It has three pairs of legs • It has one pair of antennae• It has three body segments (head, thorax, abdomen) • It has compound eyes• It has wings

Specimen B (Spider) belongs to Class Arachnida. Any two of the following reasons:• It has four pairs of legs • It has one pair of chelicerae• It has two body divisions (cephalothorax and abdomen) • It has simple eyes*

*The answer “it has simple eyes” is not acceptable if the eyes are not visible in the specimen

Specimen C (Crab or Crayfish) belongs to Class Crustacea. Any two of the following reasons:• It has five pairs of walking legs • It has a thick, hard exoskeleton (carapace)• It has two pairs of antennae • It has one pair of compound eyes• It has two body divisions (cephalothorax and abdomen)

-8-

f) • The diagram must have a title. • The diagram should be drawn in pencil.• Labeling lines should be drawn with a ruler.• The diagram must be accurate. It must show six legs, two antennae, and one wing. The legs must be jointed.

Lateral view of specimen A (grasshopper)

Arthropods Practical #2 Solutionsa) A – Cockroach B – Housefly C – Spider D – Termiteb) Phylum Arthropoda. Any two of the following reasons:

• They have jointed appendages/jointed legs • They have bilateral symmetry• They have a segmented body • They have an exoskeleton*

* The answer should not say “exoskeleton made of chitin” because the chitin is not actually visible in the specimensc) Specimen A (cockroach), Specimen B (housefly), Specimen D (termite)d) Specimen C. It belongs to class Arachnida. Any two of the following reasons:

• It has four pairs of legs • It has one pair of chelicerae• It has two body divisions (cephalothorax and abdomen) • It has simple eyes*

*The answer “it has simple eyes” is not acceptable if the eyes are not visible in the specimen

e) Students should answer this question by observing the specimens and writing their own observations of the differences. They should not try to memorize or guess the answers.

All of the following answers are acceptable. Also accept any other reasonable answers.

Specimen A (Cockroach) Specimen B (Housefly)

Has hard, leathery wings Has soft, fragile wings

Larger Smaller

Dark brown colour Black colour

Has longer antennae Has shorter antennae

Does not have hairs on its body Has hairs on its body

Has two pairs of wings* Has one pair of wings

*Students will have to lift the wings of the cockroach to observe the second pair of wings. The second pair of wings is beneath the first pair.

f)• The diagram must have a title. • The diagram should be drawn in pencil.• Labeling lines should be drawn with a ruler.• The diagram must be accurate. It must show eight legs and two body divisions. • The following should be labeled: abdomen, cephalothorax, eyes, leg, chelicerae

Dorsal view of specimen C (spider)

-9-

DIAGRAMS AND CHARACTERISTICS OF COMMON ARTHROPODS The most common arthropods on the biology WASSCE practical are:

• Grasshopper • Cockroach • Soldier termite • Weevil • Tick • Housefly • Mosquito larva • Butterfly • Spider

The WASSCE sometimes asks about the following arthropods, but less often: • Honeybee • Caterpillar • Maggot • Adult mosquito • Crab

You should be able to draw and label diagrams of the common arthropods on the WASSCE. You shouldalso be able to answer questions about their characteristics, adaptations, and economic importance.

The following pages summarize the main characteristics of the common arthropods on the WASSCE. However, you should remember that the biology WASSCE practical is not only about memorization. It is also about observation. Do not panic if the practical asks a question that you have not studied. You will often be able to answer it by looking closely at the specimen and writing your observations.

BEE (HONEYBEE)Bees are social insects that live in colonies. Each colony has three types (castes) of bees: queen, drones, and workers. The workers are the most common and they are the bees that we usually see flying around.

Class: Insecta

Habitat: Beehive

Food: Nectar, pollen

Type of metamorphosis: Complete

Economic Importance• Pollinates flowers• Produces honey• Produces wax, which is used in candles and

polishes• Sting is painful and sometimes causes death

Adaptations of worker bees:• Sting for defense• Pollen basket for carrying pollen to the beehive• Wings for flying to flowers and beehive• Antennae for sensing the environment• Proboscis for sucking nectar from flowers

Castes of bees: A bee colony has three types (or castes) of bees:

• The queen lays eggs• The drone fertilizes the eggs• The workers collect food, build and clean the

hive, and care for the larvae

Dorsal view of a worker honeybee

-10-

BUTTERFLYClass: Insecta

Habitat: Gardens, farms, flowers, trees

Food: Nectar from flowers, fruit

Trophic level: Primary consumer

Economic Importance:• Pollinates flowers• Destroys fruits by sucking their juice


Name of larva: Caterpillar

Observable features unique to butterflies:• Large, broad wings• Scales on wings• Eyespots on wings (eyespots are circles that look like eyes)• Clubbed antennae (ends of antennae are wide and round)• Mouthpart is a long, coiled proboscis

Adaptations: • Broad wings for flying• Long, thin proboscis for drinking nectar• Large compound eyes provide good vision• Eyespots provide protection by distracting predators• Long clubbed antennae for sensing the environment

Dorsal view of a butterfly Mouthparts of a butterfly

CATERPILLARThe caterpillar is the larva of the butterfly. After it grows larger, it changes into a pupa, which then develops into an adult butterfly.

Class: Insecta

Habitat: Gardens, leaves, trees

Food: Vegetation (leaves)


Next stage of metamorphosis: Pupa

Name of adult: Butterfly

Economic Importance:• Destroys leaves of crops• Some caterpillars produce silk

Adaptations:• Strong mouthparts for chewing vegetation• Claspers for holding tightly to leaves• Legs and prolegs for climbing• Simple eyes for vision

• Green colour blends with leaves and helps caterpillarhide from predators

• Osmeterium releases a foul smell to scare predators*

*The osmeterium is usually hidden in the caterpillar’s thorax (behind the head). When the caterpillar is attacked, the osmeterium comes out from the thorax and releases a bad smell. It also scares predators because it looks like the tongue of a snake.

Lateral view of a caterpillar

-11-

COCKROACHClass: Insecta

Habitat: Cupboards, cracks, wardrobes,dark corners, toilets, waste bins

Feeding habit: Omnivore

Trophic level: Secondary consumer

Economic Importance: • Destroys food and clothes • Spreads dirt and germs

Type of metamorphosis: Incomplete

Adaptations:• Long antennae for sensing the environment• Flat body allows movement through cracks

and crevices• Brown colour provides camouflage in dark

environments• Wings for flying and escaping from predators• Strong mouthparts for chewing food• Tough exoskeleton protects against injury

and prevents body from drying out

Notes on cockroach diagramSpiracles are used for breathing. They are openings that allow air to enter the body.

There are two cerci. They are used to sense the environment. (Cerci is plural. The singular is cercus).

Anal styles are only found in males. You can identify whether a cockroach is male for female by checking if it has anal styles.

This diagram shows an adult cockroach. The juvenile (nymph) does not have wings. It also has smaller cerci.

GRASSHOPPERClass: Insecta

Habitat: Fields, grasslands, gardens, farms

Food: Vegetation (leaves)


Economic Importance• Eats leaves of crops and reduces crop yield• Spreads diseases to crops• Can be eaten as a source of protein


Adaptations:• Long hindlegs for jumping• Strong mouthparts for chewing leaves• Green or brown colour for camouflage from

predators• Long antennae for sensing the environment• Wings for flying and escaping predators• Tough exoskeleton prevents desiccation (this

means it keeps the body from drying)

Lateral view of a grasshopper

-12-

HOUSEFLYClass: Insecta

Habitat: Decaying organic matter, rotting food

Method of feeding: The housefly first secretes saliva into its food. Enzymes in the saliva digest the food. The housefly then sucks up the digested food with its proboscis.


Name of larva: Maggot

Economic Importance• Spreads disease • Causes food to spoil

Adaptations:• Proboscis allows housefly to suck up its food• Halteres provide balance during flight• Setae are used for sensing the environment• Claws can cling tightly to surfaces• Glandular pads secrete a sticky substance

that allows fly to walk on vertical surfaces

Notes on housefly diagram• Halteres provide balance while flying• Setae sense the environment

Dorsal view of a housefly

MAGGOTThe maggot is the larva of the housefly. After it grows larger, it changes into a pupa, which thendevelops into an adult housefly.

Class: Insecta

Habitat: Decaying organic matter, rotting food

Food: Spoiled food, rotting meat, dead animals

Trophic level: Decomposer

Name of adult: Housefly


Economic Importance• Causes food to spoil• Can be used as food for chickens and fish• Breaks down organic matter and returns

nutrients to the soil

Adaptations:• Has a hooked mandible for tearing food• Spiny pads help with movement• Soft, flexible body allows it to move by crawling• Has spiracles for gaseous exchange

Methods of controlling maggots• Preserve food well to prevent spoiling• Cover food to protect it from flies• Keep sewage and trash far from human houses• Use insecticides to kill flies

Lateral view of a maggot

-13-

MOSQUITO LARVAClass: Insecta

Habitat: Stagnant water (pond, swamp, puddle)

Food: Algae and microbes

Method of feeding: The mouth brushes sweep water toward the mouth, then small hairs filter algae and other food out of the water

Name of adult: Mosquito

Adaptations:• Siphon (breathing tube) reaches above the

water, allowing the larva to breathe• Mouth brushes filter food from the water• Antennae sense the environment• Horny jaw is used to chew solid foods• Hairs on the abdomen help the larva attach to

the surface of the water• Tough feathery hairs help with defense• Long cylindrical body can be used for

wriggling movement in the water

Economic Importance : • Mosquito larvae are a source of food for fish• Adult mosquitos carry diseases such as malaria,

dengue, and yellow fever

Control methods:• Drain all sources of standing water• Stock ponds with fish that eat mosquito larvae• Spray oil over water so larvae cannot breathe• Use insecticides to kill the larvae

Diagram of a mosquito larva

SPIDERClass: Arachnida

Food: Insects

Adaptations:• Chelicerae have poison fangs for killing prey• Spinnerets make silk for building webs• Has simple eyes for seeing• Pedipalps are sensitive to touch and are used to

sense the environment

Economic Importance• Can be used for biological control of insect pests• Some are poisonous and can harm humans

-14-

TERMITE (SOLDIER TERMITE)Termites are social insects that live in colonies. Each colony has five types (castes) of termite: queen, king, workers, soldiers, and winged reproductives. The soldier is the most common termite caste on the WASSCE.

Class: Insecta

Habitat: Termite mound (termitarium), soil

Food: Rotting wood


Economic Importance:• Destroys furniture and houses made of wood• Can be eaten as a source of protein • Damages crops• Termite burrows help aerate the soil

Methods of control:• Wooden buildings should be built on a treated

concrete foundation• Buildings should be checked for termites and

treated with insecticide if termites are presentFunction: Defense of termite colony

Adaptations to function:• Strong jaws for defense• Large, hard head for protection• Antennae for sensing the environment

Features of interest: • Soldier termites do not have eyes. They are

blind.• Soldier termites do not have mouthparts for

chewing food. The workers chew and digest the food, then regurgitate it and feed it to the soldiers.

Dorsal view of a soldier termite This termite can be identified as a soldier because

it has a large head and large jaws (mandibles)

TICKClass: Arachnida

Habitat: Lives on the skin of mammals such as humans, cows, goats, and dogs

Food: Drinks the blood of mammals

Mode of nutrition: Parasite

Economic Importance• Spreads disease• Can cause weakness or poor growth in livestock

Methods of controlling ticks:• Picking ticks off the skin by hand• Use of insecticides to kill ticks in livestock

Diagram of a tick

-15-

WEEVILClass: Insecta

Habitat: Dry foods such as grains and beans

Food: Rice, maize, beans, nuts, seeds


Adaptations:• Strong rostrum allows it to bore holes in grains• Hard outer wings (elytra) protect the body• Antennae are used to sense the environment• Has a small size, which allows it to crawl inside

of grains• Has wings for flying to new locations

Economic importance• Damages stored grain so it cannot be sold• Reduces the nutritional value of grain• Destroys seeds so they cannot be planted

Methods of controlling weevils:• Treat stored grains with insecticides• Irradiate stored grains to kill weevils• Dry grains thoroughly before storing• Remove infected sacks of grain so that the

remaining grain is not contaminated

Disadvantages of control methods: Insecticides may cause pollution and harm to human health

Dorsal view of a grain weevil

-16-

Arthropod PracticalsThese practicals begin with practical #3. Please note that practicals #1 and #2 are in part 1 of the arthropod notes. However, you can also start teaching with practical #3 if you do not have much time.



A – Cockroach B – Soldier termite


2) Place each specimen in a jar or on a plate. Label it with the letter given above. Do not write the nameof the specimen. Do not tell the students the names of the specimens.


a) Identify each specimen without giving reasons.b) Suggest a possible habit for: (i) Specimen A (ii) Specimen Bc) (i) State three features of Specimen A which adapt it to its habitat.

(ii) Name one feature of Specimen B used for defense. (iii) Name two ways in which Specimen B is of economic importance.

d) Draw a labeled diagram 8-10 cm long of the dorsal view of Specimen A. Remove the wings of Specimen A before drawing the diagram.

e) (i) State three similarities between Specimens A and B.(ii) In a tabular form, give three differences between Specimens A and B.

- Solutions to questions are on pg 22 -


These instructions are for the TEACHER ONLY. Do not give this information to your students!1) Gather the following specimens: C – Grasshopper D – Butterfly2) Place each specimen in a jar or on a plate. Label it with the letter given above. Do not write the name

of the specimen. Do not tell the students the names of the specimens.


a) Identify each specimen without giving reasons.b) (i) Name the phylum to which Specimens C and D belong.

(ii) Give two reasons for your answer in b(i).c) State three observable differences between Specimens C and D.d) Give the type of metamorphosis in (i) Specimen C (ii) Specimen De) (i) State the trophic level of Specimen C.

(ii) State where Specimen C can be found in nature.(iii) State three observable adaptive features of Specimen C to its habitat.(iv) State two ways in which Specimen C is of economic importance.

f) Make a drawing, 8-10 cm long, of the dorsal view of Specimen D and label it fully.

- Solutions to questions are on pg 23-

-17-


These instructions are for the TEACHER ONLY. Do not give this information to your students!1) Gather the following specimens: E – Grain weevil F – Spider




a) Identify each specimen without giving reasons.b) (i) Name the class to which each specimen belongs.

(ii) List three observable features of the class to which Specimen E belongs. (iii) List three observable features of the class to which Specimen F belongs.

c) (i) State two observable similarities between Specimens E and F.(ii) In a tabular form, state three observable differences between Specimens E and F.

d) (i) State one observable feature by which Specimen E obtains its food.(ii) State one way in which Specimen E is of economic importance.(iii) State two ways of preventing the activity of Specimen E.

e) Draw a 8-10 cm long diagram of the dorsal view of Specimen F and label it fully.



These instructions are for the TEACHER ONLY. Do not give this information to your students!1) Gather the following specimens: G – Housefly H – Maggot I – Mosquito larva

*These specimens are very small. If possible, you should provide magnifying glasses (handlens) to your students so they can see the specimens better.



a) Identify each specimen without giving reasons.b) (i) State where Specimen H can be found in nature.

(ii) State two observable adaptive features of Specimen H to its environment.(iii) Give the relationship between Specimens G and H.

c) (i) State the habitat of Specimen I.(ii) Describe two observable features in Specimen I which suggests its habitat.(iii) State two ways of controlling Specimen I.

d) (i) State two observable similarities between Specimens H and I.(ii) State three observable structural differences between Specimens H and I.

e) Draw a diagram 10-12 cm long of the dorsal view of Specimen G and label it fully.


-18-

Arthropod Alternative to Practical #1 (WASSCE 2018)

a) (i) Identify organisms A and B. (ii) Name the parts labeled I to X.

b) State one function each of the parts labeled VI, VIII, IX, and X. c) Name the specific habitats of organisms A and B. d) State three structural adaptations of organism A to its mode of life. e) (i) State three structural similarities between organisms A and B.

(ii) State three structural differences between organisms A and B. f) (i) Name the class of organisms A and B.

(ii) State three reasons for the answer in (f)(i) above.g) State one biological importance of organism A.

Arthropod Alternative to Practical #2 (WASSCE 2016)The diagram below is an illustration of an organism. Study it and answer questions 1(a) to 1(e).

a) (i) Identify the organism.(ii) Classify the organism into its phylum and class.(iii) State two reasons each for the answers in 1(a)(ii)

b) (i) Name the parts labelled I to VIII(ii) State one function each of the parts labelled I, II, III, IV, VI, and VII.

c) (i) Suggest two habitats of the organism.(ii) State three ways by which the organism is of economic importance.

d) State the type of metamorphosis undergone by the organism.e) (i) State the sex of the organism.

(ii) Give one reason for the answer in 1(e)(i).

- Solutions are on pg 26 and 27 -

-19-

Arthropod Alternative to Practical #3 (WASSCE 2016)Diagrams D, E, F, and G are illustrations of organisms of the same species. Study them and answerquestions (a) to (h).

a) Name the: (i) Phylum (ii) Class of the organismsb) Give two reasons each for the answers in (a).c) (i) Which of the organisms are male? (ii) Give one reasons for the answer in (c)(i).d) State three observable differences between organisms D and G.e) State one observable biological advantage each that: (i) D has over F (ii) F has over Df) State four observable features that show variation in organisms D, E, F, and G.g) Suggest two possible habitats of the organism.h) State three ways in which the organisms are of economic importance.

Arthropod Alternative to Practical #4 (WASSCE 2012)

a) (i) Identify the organism in the diagram.(ii) Name the parts labeled I to X.

b) State the function of the parts labeled I, II, III, IV, and VII.c) (i) List four observable features of the organism and state how they adapt the organism

to its mode of life.(ii) State two ways in which the organism is of economic importance.(iii) State two ways by which the activities of the organism can be controlled.

d) (i) State the class of the organism. (ii) Give three reasons for placing the organism in the class named in (d)(i) above.

e) State the:(i) Habitat (ii) Diet (iii) Type of metamorphosis undergone by the organism

-Solutions are on pg 28 and 29 -

-20-

Test Your Knowledge: Arthropod Questions from Past WASSCE Tests - Solutions are on pg 30 -

1) The following insects undergo incomplete metamorphosis exceptA. Termite B. Cockroach C. Butterfly D. Locust

The diagram at right is an illustration of the life cycle of an insect.Study it and answer the questions that follow.2) The adult insect in this life cycle is

A. Housefly B. Butterfly C. Cockroach D. Mosquito

3) The larva is also known as A. Nymph B. Maggot C. Caterpillar D. Chrysalis

4) Which of the following insects exhibits incomplete metamorphosis?A. Butterfly B. Moth C. Mosquito D. Housefly E. Cockroach

5) An economic importance of weevils is that theyA. Destroy crops B. Pollinate flowers C. Destroy grains D. Transmit disease to man

6) Houseflies are economically important because theyA. Hover around all places C. Are vectors of numerous diseasesB. Deprive man of the good taste of food D. Encourage the decay of organic substances

7) Bees are of great importance to the farmer because theyA. Provide him with honey C. Sting crop pests to deathB. Pollinate flowers D. Destroy flowers by sucking nectar from them

8) When oil is used to cover the surface of stagnant water bodies as a control measure against malaria, theintention is to

A. Prevent evaporation of water C. Prevent the adult flies from laying eggs in the waterB. Suffocate the larvae and pupae D. Destroy the source of food for the larvae

9) The spinnerets found in the caterpillar of butterfly are used forA. Protection against predators C. Movement on twigsB. Feeding on vegetation D. Production of silk thread

10) One feature that distinguishes a nymph from an adult cockroach is theA. Number of the thoracic subdivisions C. Presence or absence of anal styleB. Presence or absence of cerci D. Presence or absence of wings

11) Social insects are those whichA. Possess rostrum for feeding C. Have different formsB. Live in organized communities D. Live in termitaria

12) Which of the following is a social insect?A. Mosquito B. Butterfly C. Honey bee D. Grasshopper E. Cockroach

13) The following are social insects exceptA. Wasps B. Termites C. Bees D. Cotton stainer

14) A termite with a relatively large head and powerful jaws is likely to be aA. King B. Queen C. Soldier D. Reproductive

15) Which of the following is not correct of the worker caste in a termite colony? TheyA. Constitute the majority of the termite populationB. Take care of the eggs and nurse the newly hatched nymphsC. Keep enemies away by blocking the tunnels with their headsD. Clean, repair, and expand the nestE. Feed and clean the king and queen

16) Honeybee workers carry out the following functions exceptA. Laying eggs B. Building nests C. Cleaning the nests D. Gathering food

-21-

SOLUTIONS: Arthropod Practicals

Arthropod Practical #3 Solutionsa) A – Cockroach B – Soldier termiteb) (i) Any one of the following: Cupboards, wardrobes, cracks in walls, cartons, waste bins, toilets, dark corners

(ii) Any one of the following: Termite mound, termite nest, soil, rotting logs, walls of wooden buildingsc) (i) Adaptations of cockroach (any three):

• Dorsoventrally flattened body for easy movement through cracks and crevices• Hard forewings protect the delicate hindwings from damage• Brown colour provides camouflage in dark areas• Wings for flying and escaping from predators• Long antennae for sensing the environment• Strong mouthparts/mandibles for chewing• Strong hindlimbs for rapid movement• Body has spiracles for gaseous exchange

(ii) Strong jaws/mandibles for biting attackers(iii) Economic importance of termites (any two):

• Destroys furniture and houses made of wood• Damages some crops• Source of protein (can be eaten)• Improves aeration of soil by burrowing into the soil• Aids decay and recycling of nutrients by bringing dead organic matter into the soil

d) Diagram must include the following: • Title • Magnification written in title (it will be between

x 1 and x 4 depending on the cockroach used) • Straight lines drawn with a ruler • Neat labels written horizontally • The following must be included in the diagram: - Spiracles on both sides of the body

- Two cerci located on the abdomen- Segments drawn on body and also on legs and antenna

• Anal styles are on MALE COCKROACHES only. You should not draw anal styles if your specimen is female.

• Wings should NOT be drawn. The practical instructions say to remove the wings before drawing.

e) (i) Similarities between cockroach and soldier termite (any two):• Three body segments (head, thorax, and abdomen) • Three pairs of legs/six legs • Hard exoskeleton• Jointed legs• One pair of antennae

(ii) Differences between cockroach and soldier termite (any three)

Specimen A (Cockroach) Specimen B (Soldier Termite)

Small head Large head


Has compound eyes Does not have eyes (blind)

Dark brown colour Light brown colour

Small mandibles (small jaws) Large mandibles (large jaws)

-22-

Dorsal view of cockroach with wings removed x1

Arthropod Practical #4 Solutionsa) C – Grasshopper D – Butterflyb) (i) Phylum Arthropoda

(ii) Reasons for Phylum Arthropoda (any two):• Has paired, jointed legs • Has a segmented body• Has bilateral symmetry • Has an exoskeleton made of chitin

c) Differences between Specimens C and D (any three):Specimen C (Grasshopper) Specimen D (Butterfly)

Has mandibles Has a proboscis

Hind legs large and muscular Hind legs smaller and less muscular

Wing is hard/leathery Wing is soft/membraneous

Wings are green or brown Wings have many different colours

Smooth abdomen Hairy abdomen

Surface of wing is not powdery/does not have scales

Surface of wing is powdery/has scales

Antennae are not clubbed/rounded/knobbed

Antennae are clubbed/rounded/knobbed

d) (i) Incomplete metamorphosis (ii) Complete metamorphosis

e) (i) Primary consumer(ii) Habitat of grasshopper (any one): Fields, grasslands, gardens, farms(iii) Adaptations of grasshopper (any three):

• Long hindlegs for jumping and escaping predators• Wings for flying• Antennae for sensing the environment• Strong mouthparts for chewing on vegetation• Spiracles for gaseous exchange• Short forelegs act as shock absorbers when landing after a jump• Thick forewings protect the fragile inner wings• Compound eyes are used for seeing the environment• Tough exoskeleton provides protection from desiccation and injury

(iv) Economic importance of grasshopper (any two):• Eats leaves of crops / damages crops• Spreads diseases to crops• Can be eaten as a source of protein

f) Diagram must include the following: • Title • Magnification written in title (it will be between

x 0.5 and x 1.5 depending on the butterfly used) • Straight lines drawn with a ruler • Neat labels written horizontally • The following must be clearly drawn: - Antennae are clubbed (they have round ends)

- - Body has 3 divisions (head, thorax, abdomen)- - Forewings are wider than hindwings

-23-

Arthropod Practical #5 Solutionsa) E – Grain weevil F – Spiderb) (i) Specimen E (Grain weevil) – Class Insecta

Specimen F (Spider) – Class Arachnida(ii) Observable features of Class Insecta (any three):

• Three pairs of legs / six legs • Three body divisions (head, thorax, and abdomen) • One pair of compound eyes • Presence of wings • One pair of antennae

(iii) Observable features of Class Arachnida (any three): • Four pairs of legs / eight legs • Two body divisions (cephalothorax and abdomen) • One pair of chelicerae • Presence of simple eyes

c) (i) Similarities between spider and grain weevil (any two): • Both have jointed legs • Both have bilateral symmetry • Both have segmented bodies • Both have an exoskeleton

(ii) Differences between spider and grain weevil (any three):

Specimen E (Grain weevil) Specimen F (Spider)

Has three pairs of legs / six legs Has four pairs of legs / eight legs

Has three body segments (head, thorax, and abdomen)

Has two body segments (cephalothorax and abdomen)

Has a rostrum Does not have a rostrum


Has one pair of antennae Does not have antennae

Does not have chelicerae Has a pair of chelicerae

Does not have spinnerets Has spinnerets

d) (i) It has a rostrum for drilling holes in grain.(ii) Damages stored grain/destroys grain and beans/destroys seeds so they cannot be planted(iii) Methods of controlling weevils (any two):

• Treat stored grains with insecticides• Irradiate stored grains to kill weevils• Dry grains thoroughly before storing

e) Diagram must include the following: • Title • Magnification written in title (it will be between

x 1 and x 10 depending on the spider used) • Straight lines drawn with a ruler • Neat labels written horizontally • The following should be clearly drawn: - 2 body segments (cephalothorax and abdomen) - 1 pair of chelicerae and 1 pair of pedipalps - 1 pair of spinnerets attached to the abdomen - 4 pairs of jointed legs, all attached to the cephalothorax

Diagram of dorsal view of a spider x 2

-24-

Arthropod Practical #6 Solutionsa) G – Housefly H – Maggot I – Mosquito larva

b) (i) Habitat of maggot (any one): Decomposing organic matter/faeces/meat/rotting food(ii) Adaptations of maggot (any two):

• Has a hooked mandible for movement and feeding• Has small pads on segments to aid with movement• Has spiracles for breathing

(iii) Specimen G is the adult form of Specimen H / Specimen H is the larva of Specimen G

c) (i) Habitat of mosquito larva (any one): Stagnant water, pond, swamp, puddle, riverbank (ii) Features which suggest that mosquito larvae live in water (must write all two)

• Presence of breathing tubes / siphons (allows larva to breathe without leaving the water) • Presence of tail plates (helps larva to move through the water)

(iii) Methods of controlling mosquito larvae (any two): • Drain all sources of standing water • Spray oil over water so larvae cannot breathe • Use insecticides to kill the larvae • Stock ponds with fish that eat mosquito larvae

d) (i) Similarities between maggot and mosquito larva (any two): • Both have a segmented body • Both have a mouth • Both have spiracles • Both are cylindrical / both have an elongated body

(ii) Differences between maggot and mosquito larva (any three):

Specimen H (maggot) Specimen I (mosquito larva)

Does not have mouth brushes Has mouth brushes

Does not have bristles Has bristles

Does not have anal gills Has anal gills

Anterior end is pointed Anterior end not pointed

Posterior end is blunt (wide) Posterior end is not blunt (wide)

Does not have antennae Has antennae

Two body divisions (head and trunk) Three body divisions (head, thorax, and abdomen)

Hook present Hook absent

Siphon / breathing tube absent Siphon / breathing tube present

Pad present Pad absent

Eye absent Eye present

e) Diagram must include the following: • Title • Magnification written in title (it will be

between about x 10 and x 15 depending onthe housefly used)

• Straight lines drawn with a ruler • Neat labels written horizontally • The following should be c learly drawn:

- Veins should be included on wings - Legs should be segmented - Hairs should be drawn on body - Halteres should be drawn and labeled

-25-

Diagram of dorsal view of housefly x 10

SOLUTIONS: Arthropods Alternative to Practical Questions

Alternative to Practical #1 SolutionsNote: If answers are written with a slash (/), it means any of the answers are correct. For example, if the answer says garden/farm, this means a student who wrote “garden” is correct, but a student who wrote “farm” is also correct.

a) (i) A – Butterfly or Papillo sp. B – Housefly or Musca sp.(ii) I – Head II – Antenna III – Thorax IV – Wing / forewing V – Abdomen

VI – Antenna VII – Head VIII – Compound eye IX – Wing / forewing X – Leg*Students will not receive marks if they use the wrong adjective. For example, if the answer is either wing or

forewing, they will get marks for writing “wing”. However, they will not get any marks for writing “hind wing”.

b) VI (Antenna) – For feeling / sensitivity / touch / to smell / to feel vibrationsVIII (Compound eye) – For seeing / sight / visionIX (Wing) – For flying / flight /balancingX (Leg) – For walking / crawling / running

c) A – Garden / farm / flowering plants / trees B – Latrines / toilets / sewage / refuse dumps / decaying organic matter

d) Any three of the following:• Long clubbed antennae for sensing the environment • Long / broad wings for flying• Long thin proboscis (mouthpart) for sucking nectar • Large compound eyes for vision

(e) Any three of the following:• Both have wings• Both have three body divisions (head, thorax, and abdomen)• Both have two antennae• Both have two compound eyes• Both have a segmented body

(ii) Any three of the following differences:

Butterfly Housefly

Broad wings Narrow wings

Antennae are clubbed/knobbed Antennae are not clubbed/knobbed

Long antennae Short antennae

Smaller compound eyes Larger compound eyes

Has scales Does not have scales

Has hind wings Hind wings reduced to halteres

Simple eyes absent Simple eyes present

Hair absent Hair present

(f) (i) Insecta(ii) Any three of the following:

• Three body divisions (head, thorax, and abdomen)• Three pairs of legs / six legs• Presence of a pair of antennae• Presence of compound eyes• Presence of wings

(g) It pollinates flowers/it serves as a source of food for some organisms

-26-

Alternative to Practical #2 SolutionsNote: If answers are written with a slash (/), it means any of the answers are correct. For example, if the answer says garden/farm, this means a student who wrote “garden” is correct, but a student who wrote “farm” is also correct.

a) (i) Cockroach(ii) Phylum Arthropoda, Class Insecta(iii) Reasons for Phylum Arthropoda (any two)

• Has paired, jointed legs• Has bilateral symmetry• Has a segmented body• Has an exoskeleton made of chitin

Reasons for Class Insecta (any two)• Has three pairs of legs• Has wings• Has three body divisions (head, thorax, and

abdomen)• Has one pair of antennae• Has compound eyes

b) (i) I – Eye / compound eye II – Antenna III – Prothorax IV – Forewing V – Hindwing VI – Spiracle VII – Cercus VIII – Anal style

(ii) I – for seeing II – to sense the environment / to smell III – connects the head to the mesothorax

IV – protects the hindwings / for flying / for locomotionVI – for gaseous exchange / allows air to enter and leave the body VII – to sense vibrations / to sense the environment

c) (i) Habitat (any two): • Cupboards • Wardrobes • Cracks in walls • Cartons • Waste bins • Pit toilets • Dark corners

(ii) Economic importance (any three): • Carries disease • Destroys books and clothing • Contaminates food • Has a bad smell and is a nuisance in the home

d) Incomplete metamorphosise) (i) Male

(ii) It has anal styles

-27-

Alternative to Practical #3 Solutionsa) (i) Phylum Arthropoda (ii) Class Insecta

b) (i) Reasons for Phylum Arthropoda (any two)• Has jointed appendages• Has an exoskeleton made of chitin• Has a segmented body• Has bilateral symmetry

(ii) Reasons for Class Insecta (any two)• Has three body divisions (head, thorax, and abdomen)• Has three pairs of legs / has six legs• Has one pair of compound eyes• Has one pair of antennae• Has wings

c) (i) D and F are male (ii) They have anal styles

d) Differences between D and G (any three)

D G

Has longer antennae Has shorter antennae

Has veins on wings*(or veins on wing are clearly shown)

Does not have veins on wings* (or veins on wings are not clearly shown)

Narrower abdomen Broader abdomen

Has anal style (male) Lacks anal style (female)

Spiracles absent Spiracles present

*”Stripes on wings” is not an acceptable answer. Students must use the word veins.

e) (i) Biological advantage of D over F (any one)• D has wings to fly and escape predators, while F has only wing stubs and cannot fly• D has longer antennae for better sensing of the environment• D has long wings that protect the abdomen, while F has only small wing stubs that cannot protect the

abdomen

(ii) Biological advantage of F over D:• F is smaller and can hide more easily

f) Other observable features that show variation (any four)• Length of antennae • Length of wings• Venation of wings (presence or absence of veins on wings)• Body size (or size of abdomen)• Presence or absence of anal style

g) Possible habitats (any two)• Dark corners • Crevices or cracks in walls • Cupboards • Cartons • Waste bins • Pit toilets

h) Economic importance (any three)• Carries dirt and contaminates food• Spreads disease• Has a bad smell and is a nuisance in the home• Destroys possessions such as clothes and books (its faeces can stain clothes and books)

-28-

Alternative to Practical #4 Solutionsa) (i) Grasshopper

(ii) I – Antenna VI – Wing II – Eye / compound eye VII – Hindleg III – Mandibles / mouthparts VIII – Thorax IV – Spiracle IX – Head

V – Abdomen X – Foreleg

b) I – Senses the environment II – Provides vision/allows it to see the environment III – Chews food/cuts food into smaller pieces IV – Used for gaseous exchange/allows gases to enter and leave the body VII – Used for jumping/used for rapid movement

c) (i) Any four of the following:• Long hindlegs – For jumping and escaping predators• Wings – For flying to search for food or escape from predators • Antennae – For sensing the environment• Strong mouthparts – For biting and chewing tough vegetation• Spiracles – For gaseous exchange• Short forelegs – Act as shock absorbers when landing after a jump• Thick forewings – Protect the fragile inner wings• Compound eyes – Provide good vision which allows it to see predators and food sources• Tough exoskeleton – Protects from desiccation and injury

Note: “Green or brown colour for camouflage” is incorrect because the color is not visible in the picture

(ii) Economic importance (any two of the following):• Eats leaves of crops / damages crops• Spreads diseases to crops• Can be eaten as a source of protein

(iii) Methods of control:• Use insecticides to kill the grasshoppers• Allow chickens to walk around infested fields and eat the grasshoppers

d) (i) Class Insecta

(ii) Reaso ns for Class Insecta (any three): • Has three body divisions (head, thorax, and abdomen)• Has three pairs of legs / has six legs• Has one pair of compound eyes• Has one pair of antennae• Has wings

e) (i) Fields / Grasslands / Gardens / Farms (ii) Vegetation / Leaves (iii) Incomplete metamorphosis

-29-

SOLUTIONS: Arthropod Questions from Past WASSCE Tests1) C. Butterflies undergo complete metamorphosis. This means that they have 4 stages of development: egg,

larva, pupa, and adult.2) B. This is a diagram of butterfly metamorphosis. Hence, the larva is called a caterpillar and the adult is called

a butterfly.3) C. See the explanation in the answer for question 2.4) E. Cockroaches undergo incomplete metamorphosis. This means that the juveniles resemble the adults and

there is no pupa stage.5) C. Grain weevils feed on grains and beans. They seriously damage grains by eating the insides of them.6) C. A vector is something that spreads disease. Houseflies spread disease because they feed on faeces and

trash as well as human food. When they land on food, they bring germs from the faeces or trash with them.7) B. Bees are very important as pollinators. When they fly from flower to flower, they carry pollen with them.

(Bees are also useful because they make honey, but their role as pollinators is even more important).8) B. Suffocate means to die from a lack of oxygen. Oil prevents mosquito larvae and pupae from reaching

above the surface of water to obtain oxygen. As a result, they die from suffocation.9) D. Caterpillars use silk threads to balance and hold on to leaves and branches. The thread is made by

spinnerets located on the abdomen.10) D. Nymphs are young, immature cockroaches. They do not have wings, but adult cockroaches have wings.11) B. Social means to live together in a community. Ants, termites, and bees are all social insects.12) C. Bees are social insects because they live together in a hive and divide the work between different

members of the hive.13) D. The cotton stainer is a beetle that lives on cotton plants. It lives alone and is not a social insect. 14) C. The soldier termite must have a large head and strong jaws because it is responsible for defending the

termite mound from attackers.15) C. Worker termites are responsible for building the termite mound, finding food, feeding the king and

queen, and taking care of the young. However, they do not defend the termite mound from enemies. The soldiers are responsible for defense.

16) A. The queen honeybee is responsible for laying eggs. The workers collect food, build the hive, and keep thehive clean.

-30-

PHYLUM ARTHROPODA · ARACHNIDA 2 4 None Simple Have chelicerae CRUSTACEA 2 5 2 pairs Compound...

Documents

Transcript of PHYLUM ARTHROPODA · ARACHNIDA 2 4 None Simple Have chelicerae CRUSTACEA 2 5 2 pairs Compound...