Bellwork: February 19

• Copy the statement and question

• Underline key words

CO: I will describe and analyze the transport system in plants.

LO: I will write notes. I will draw a feedback loop. I will talk about the

transport system with my peers.

Science Fact of the Day:An ostrich's eye is bigger than its brain.

Homeostasis refers to an organisms ability to maintain a stable internal condition

Think-Pair-Share

What are some examples of things your body regulates?

**Regulate=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• Specialized cells

to increase surface area for water intake

Wheat seed

Root hairs

Fragile parts of cells that grow from the main root

They 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 are 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

Stoma position

Leaf diagram – palisade layer

CO2

Most chlorophyll

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.

Stomata are small holesIts size is controlled by 2 guard cells

closed open

The stomata’s 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

Gas exchange

Transpiration is 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.

Why Regulate Stomata

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?