STD VII General Science - Target Publications · 2. Fishes have fins on the body and scales on the...
Transcript of STD VII General Science - Target Publications · 2. Fishes have fins on the body and scales on the...
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STD. VII General Science
10810_11680_JUP
Printed at: Repro India Ltd., Mumbai
P.O. No. 59687
Written as per the revised syllabus prescribed for the academic year 2017-2018, by the Maharashtra State Bureau of Textbook Production and Curriculum Research, Pune.
PREFACE While designing the book, our main intention was to create a book that would act as a single point
of reference for students. We wanted this book to provide students, the much needed answers for
their textual questions as well as build up their knowledge quotient in the process.
General Science: Std. VII has been prepared as per the new ‘Continuous Comprehensive
Evaluation’ (CEE) evaluation system which is more child‐centric and focuses on active learning and
making the process of education more enjoyable and interesting.
We have infused the book with a liberal sprinkling of real life examples, pictorial explanations and
additional questions. Questions titled under 'Use your brain power', 'Can you tell' and a series of
'In‐text Questions', pave the way for a robust concept building.
Every chapter begins with Point wise Theory along with pictorial illustrations wherever needed. It
follows through by covering all the textual content in the format of Question ‐ Answers, Give
Reasons and a host of Formative and Summative assessments. The chapter also includes Activity
Based Questions that explain certain concepts to students in a point wise manner through the
medium of an activity. The chapter eventually ends with a Chapter wise Assessment that stands a
testimony to the fact that the child has understood the chapter thoroughly.
With absolute trust in our work, we hope, our holistic efforts towards making this book an ideal
knowledge hub for students pays off.
The journey to create a complete book is strewn with triumphs, failures and near misses. If you
think we’ve nearly missed something or want to applaud us for our triumphs, we’d love to hear
from you. Please write to us at: [email protected] A book affects eternity; one can never tell where its influence stops.
Best of luck to all the aspirants! From,
Publisher
Contents
No. Topic Name Page No.
1. The Living World : Adaptations and Classification 1
2. Plants : Structure and Function 17
3. Properties of Natural Resources 32
4. Nutrition in Living Organisms 47
5. Food Safety 64
6. Measurement of Physical Quantities 77
7. Motion, Force and Work 88
8. Static Electricity 100
9. Heat 113
10. Disaster Management 124
11. Cell Structure and Micro‐organisms 135
12. The Muscular System and Digestive System in Human Beings 153
13. Changes ‐ Physical and Chemical 168
14. Elements, Compounds and Mixtures 181
15. Materials we Use 200
16. Natural Resources 211
17. Effects of Light 230
18. Sound : Production of Sound 241
19. Properties of a Magnetic Field 253
20. In the World of Stars 264
Note: Textual Questions are respresented by * mark.
General Science
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Chapter 1: The Living World : Adaptations and Classification
1. Organisms (plants and animals) on earth show great diversity.
2. The different types of plants found on earth are as follows;
i. Plants with colourful flowers
ii. Plants which grow in water and plants which grow in deserts amid scarcity of water
iii. Plants found in snowy regions
iv. Plants which can be seen only through microscope and those which are huge in size
3. Some of the categories of animals found on earth are as follows;
i. Unicellular and multicellular
ii. Vertebrates and invertebrates
iii. Aquatic, terrestrial, amphibian, reptilian, aerial, etc.
4. In snowy regions like Kashmir, coniferous trees like pine and deodar flourish, while plants like cactus and acacia (babhul) are found in the deserts of Rajasthan.
1. Gradual changes occur in the body parts, life processes and also in the behavior of organisms which enable them to live, feed, reproduce to perpetuate themselves and protect themselves from their enemies in specific surroundings, depending upon the habitat and its geographical conditions. Such changes are called adaptations.
2. Adaptation is not a sudden process and takes place over a long period of time.
3. It is continuous and gradual.
4. The differences seen in the structure and appearance of present day animals as compared to those living thousands of years ago are the adaptations that occurred according to the prevailing conditions.
1. Some aquatic plants (plants adapted to living in aquatic environments) are tightly rooted in the soil at the bottom of the water bodies such as river, brook, pond, lake.
2. Whereas, some aquatic plants are entirely afloat and their roots are not anchored in the soil.
3. Though the stems of these plants are submerged in water, the air spaces present in petioles and stems help them in floating inside the water.
Let’s Study
1. The Living World : Adaptations and Classification
Diversity in living things
Adaptation
Adaptation in aquatic plants
Aquatic plants
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4. Also, a waxy layer is present on the surfaces of the leaves and stems of many aquatic plants. 5. Leaves of some aquatic plants are slender and thin like a ribbon which helps them to withstand fast
water currents. 1. Plants found in desert are either leafless or their leaves are
like small needles or have been modified into thorns. Due to this they lose very little water through evaporation.
2. The stem stores food and water and is therefore fleshy. 3. Since the stems perform photosynthesis in the absence of
leaves, they are green in colour. 4. The roots of these plants penetrate deep into the soil in
search of water. 5. Also a thick layer of waxy substance is present on the stems
of these plants. 1. Conifers like deodar and pine are found in snowy regions. 2. Due to their sloping branches these trees are conical in shape. 3. Conical shape of these plants prevents the snow from
accumulating on the tree and the thick bark helps the tree to withstand the heavy snowfall and extreme cold.
1. Trees, shrubs and herbs are found in forests. 2. Plants in forest compete amongst themselves for sunlight.
Therefore, the trees grow tall to get sunlight and climbers and vines grow to a great height with the support of trees.
3. Spring like tendrils which grow on the stems of some climbers is an example of adaptation.
1. A variety of bushes and grasses are found in the grasslands. 2. Soil erosion is prevented by the fibrous roots of grasses. 3. In equatorial region grasses are very tall. Animals such as elephants, tigers and deer can remain hidden
in these grasses. 4. Grasses in cold regions are very short and animals such as rabbits are found in such grasses. 5. Vast meadows are found in hilly areas and plains.
Deodar tree
Forest
Cactus
Lotus stalk Lotus leafLotus plant
Adaptation in desert plants
Adaptation in plants of snowy regions
Adaptation in plants of forest regions
Adaptation in grassland plants
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Chapter 1: The Living World : Adaptations and Classification
1. Most of the plants are anchored in the ground and are autotrophic. 2. Dodder: i. Dodder (cuscuta) are parasitic (living as a parasite) plants. ii. They consist of yellow wire like‐stems which forms the plant body. iii. Dodder is leafless and cannot perform photosynthesis. iv. It has haustorial (sucking) roots for absorbing nutrients from the
host plant. v. These roots penetrate upto the conducting vessels of the host
plant to absorb water and food. 3. Fungi: i. Fungi lack chlorophyll therefore cannot perform photosynthesis. ii. Fungi obtain their food from starchy food materials like bread
and bhakri. iii. They have root like fibers for food absorption. 4. For growth plants need nitrogen, potassium and phosphorus. 5. Plants like drosera (sundew), Venus flytrap, pitcher plant etc. that grow in
soil deficient in nitrogen, fulfill their need for nitrogen by consuming insects.
6. These plants show adaptations which serve to attract insects and hold them captive.
1. The body shape and skin of aquatic animals undergo changes. 2. Fishes have fins on the body and scales on the skin. 3. Their body tapers towards both the ends, like a spindle. 4. Fishes breathe with their gills, instead of nose and have transparent
eyelids. 5. To help them float in water, they have air bladders within the body. 7. Ducks use their legs like oars as they have webbed toes. 8. Water flows off the waxy feathers of birds like waterhen and duck. 9. Frogs can swim easily through water as they have triangular head,
webbed toes, and slippery, smooth skin. 10. Frogs have ability to breathe through the skin in water and using their nose and lungs on land.
Therefore, they can live on land as well as in water. 11. The typical colours of frog’s back help it to hide among grasses. 1. Carnivores: i. Carnivores like the wild dog, fox, tiger and lion have strong legs to run fast and capture their prey. ii. They have claws and their teeth are sharp and pointed. iii. Tigers have padded paws which help them to silently stalk their prey and capture it easily. iv. The eyes of the predatory carnivores are located in the front of their head to help them spot their
prey from a long distance. 2. Herbivores: i. The eyes of the herbivores are below the forehead, on the either side of the head. ii. This provides them wide‐angle vision and helps to protect them from predators. iii. To help them run fast taking long leaps, the legs of the herbivores are long tapering with strong
hooves.
Cuscuta
Duck
Webbed toes
Venus flytrap
Adaptation for ingestion of food in plants
Adaptation in animals
Adaptation in forest and grassland animals
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iv. Their long and freely moving ears can receive sounds from long distances and different directions. v. Blackbucks and deer have colours that merge with their surroundings. vi. They have strong teeth to chew tough plant material. 1. The severe scarcity of water is the characteristic of desert. 2. Desert animals have a thick skin to prevent loss of water
from the body. 3. They have long legs with flat and cushioned soles. 4. The nostrils are protected by folds of skin. 5. The eyelashes are thick and long. 6. In deserts, animals like snakes, spiders, lizards and rats
live in deep burrows during day time and are active at night.
1. Yak, Siberian husky dog, snow leopard, polar bear, white fox, silver fox, and mountain goat are animals
found in snowy regions. 2. Silver or white body colours, thick, long hairs on the skin are the typical characteristics of animals of
snowy region. 1. The spindle shape body of birds minimizes the resistance of air while flying. 2. A body covering of feathers, modification of forelegs into wings and
hollow bones make their body light in weight and adapted to flying. 3. The body of insects also tapers at both the ends and is light in weight. 4. Insects can fly with two pairs of wings and also walk with six stick‐like legs. 5. Bats are able to fly with the help of a thin fold of skin between forelegs
and hind legs known as patagium. 1. Garden lizard, house lizard, crocodile use their muscles for creeping. 2. They also show adaptations in soles of feet, body colour, skin, etc. For example monitor lizards and
house lizards have clawed toes and thin soles, whereas snakes have scaly skin. 1. Animals are categorised as herbivores and carnivores. 2. Special adaptations are seen in each category to make the process of feeding easy.
Tapering slender body
Claws
Wings
Adaptation in desert animals
Adaptation in animals of snowy regions
Adaptation in aerial animals
Adaptation in reptiles
Adaptation for food in animals
Desert animals
Adaptation for food in animals
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Chapter 1: The Living World : Adaptations and Classification
1. Colourful butterflies, lizards and grasshoppers get camouflaged amidst grasses, parts of plants like
stem, leaves, flowers, etc. because their colours blend with those of their surroundings.
1. Charles Darwin was a biologist who studied numerous types of plants and animals.
2. He suggested that only those organisms are likely to survive which can adapt themselves to a changing environment. This is called as the theory of ‘survival of the fittest’. This is Darwin’s first principle.
3. If an organism is born with a new beneficial characteristic and is able to survive, this change is preserved in the next generation. This is called as the theory of ‘natural selection’. This is Darwin’s second principle.
1. Different scientists have used different criteria and independently classified animals and plants.
2. A hierarchy is formed in the classification that starts with Kingdom Animalia or Kingdom Plantae; further groups and sub‐groups are formed depending upon basic similarities and differences. This is called the hierarchy of classification.
Hierarchy Mango Human
Kingdom Plantae Animalia
Phylum Anthophyla Chordata
Class Dicotyledonae Mammalia
Order Sapindales Primates
Family Anacardiaceae Hominidae
Genus Magnifera Homo
Species indica sapiens
1. Binomial nomenclature helps in identification of each organism.
2. Accordingly, scientific name has been assigned to each organism.
3. Scientific name consists of two parts‐ the first part is ‘genus’ and second ‘species’.
4. As per the guidelines of the International Code of Nomenclature all identified organisms have been assigned binomial name.
5. All the organisms of a species are so similar that irrespective of differences in height, colour, habitats and habits, they can reproduce among themselves and form new individuals like themselves.
6. For example, all domestic cats in the world belong to the same species. The same is true in the case of animals like hen, dog, cow, etc. and plants like mango, wheat, maize, etc.
Following are examples of organisms from Kingdom Plantae and Animalia classified by the binomial method of nomenclature:
Living Things Scientific Name
Dog Canis lupus familiaris
Cow Bos taurus
Hibiscus Hibiscus rosa‐sinensis
Jowar Sorghum bicolor
Adaptation blending with the surroundings
Darwin’s theory of evolution
Classification of living organisms
Binomial nomenclature by Carl Linnaeus
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1. Choose the correct option and fill in the blanks. (stem, webbed, Carl Linnaeus, waxy layer, Coniferous) i. ................... trees like pine and deodar flourish in snowy regions like Kashmir. ii. The surfaces of leaves and stems of many aquatic plants are covered with a .................... iii. The ................... of the desert plants stores water and food. iv. Ducks have ................... toes which are used like oars. v. Binomial nomenclature was discovered by .................... Answers: i. Coniferous ii. waxy layer iii. stem iv. webbed v. Carl Linnaeus 1. Plants like ................... fulfill their need for nitrogen by consuming insects. (A) Deodar (B) Pine (C) Venus flytrap and sundew (D) Cuscuta 2. ................... roots of the grasses prevent soil erosion. (A) Tap (B) Adventitious (C) Fibrous (D) Prop 3. Which of the following is not an adaptation in reptiles? (A) Scaly skin (B) Clawed toes (C) Thin soles (D) Webbed toes Answers: 1. (C) 2. (C) 3. (D) 1. Desert plants have big green leaves. Ans: Wrong. Desert plants are either leafless or their leaves are like small needles or have been modified into thorns. 2. Plants need nitrogen, phosphorus and potassium for their growth. Ans: Right. 3. Frog can live on land as well as in water. Ans: Right. 4. Desert animals have short legs with uneven and cushioned soles. Ans: Wrong. Desert animals have long legs with flat and cushioned soles. 5. The birds have hollow bones and modified forelegs into wings. Ans: Right.
Summative Assessment
Fill in the blanks
Right or Wrong? If Wrong, write the correct sentence.
Choose the correct alternative