Post on 23-Feb-2016
description
BELL WORK:
• Copy the entire question.
• Underline key words in the question.
Science Fact of the Day:An ostrich's eye is bigger than its brain.
CO: I will describe and analyze the transport system in plants.
LO: I will write notes. I will draw and discuss how homeostasis is
maintained in a plant.
Homeostasis refers to an organism’s ability to maintain a stable internal condition
Think-Pair-Share
What are some examples of things your body regulates?
**Regulate=control; maintain homeostasis***
Homeostasis is maintained through feedback loops
• Negative feedback loop = when something goes wrong the opposite thing is added to return to the original condition – Ex. Shivering
• Positive feedback loop = when something goes wrong more of the same thing is added to return to the original condition– Ex. Blood clots when you cut your finger
Is this a positive or negative feedback loop?
Today we’re going to look at how plants maintain homeostasis.
Vascular tissue: specialized tissue used to move water and nutrients throughout a plant.
Roots
• Hold plant in position
• Absorb water and minerals from the soil
Root hairs:
Fragile parts of cells that grow from the main root
Massively increase the surface area for absorption
Root hair cells (x150)
Stems:
- are supporting structures that
connect roots and leaves
- carry water and nutrients between them through the xylem and phloem
Xylem: carries water upward from the roots
to every part of the plant.
Phloem: transports food (nutrients)
produced by photosynthesis.
Leaves: organs that perform photosynthesis and contain one or more bundles of vascular tissue
Cuticle: a thick waxy layer on the top of the leaf that protects the leaf against water loss and injury.
Structures of the Leaf
Photosynthesis
Conserves water
Transports water and sugar to stem
and roots
Gas exchange
• Leaves are designed to allow carbon dioxide to get to the main chlorophyll layer at the top of the leaf
• They have small holes called stomata on the under surface
• Each hole is open & closed by 2 guard cells
Stomata: openings in the underside of the
leaf that allow carbon dioxide and oxygen to diffuse (move) into and
out of the leaf.
Guard cells: specialized cells in the epidermis
that control the opening and closing of stomata.
Stoma is a small holeIts size is controlled by 2 guard cells
closed open
Stoma function is for gas exchange in the leaf
Carbon dioxide
oxygenGuard cell
Provided plant is photosynthesising
Stomata open and close at different times of the day
When it is light the plant needs CO2 for photosynthesis so the stoma open
At night (darkness) they close
Transpiration: the loss of water through leaves
Osmotic pressure keeps a plant’s leaves and stems rigid.
Wilting results from the lack of
water—and therefore of the
pressure in a plant’s cells.
Mix-Freeze-Group
2 43• I am the vascular tissue that transports nutrients through
the plant.• I am the structure around the stomata that allows gases
to enter and exit the leaf.• I am the process during which water is lost through the
leaves.• I am the vascular tissue that transports water throughout
the plant.
5Phloem XylemGuard Cell Transpiration
Homeostasis Scenario:
What would happen to the plant if there was a drought?
Homeostasis Scenario:
What would happen to the plant if there was a flood?
Homeostasis Scenario:
What would happen to the plant if there was extra carbon dioxide in the air due to some crazy person singing to it everyday?
Homeostasis Scenario:
What would happen to the plant if there was not enough carbon dioxide in the air?
Draw your own feedback loop for nutrient uptake in a plant. Remember, most nutrients are used in photosynthesis to make
glucose.
What would the plant do if…
• There was a drought?• There was a flood?• There was extra carbon dioxide in the air due
to some crazy person singing to it everyday?• There was not enough carbon dioxide in the
air?