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?