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?