March 4, 2013Q-2 Pg. Daily Goal: We will be able to explain why leaves on trees in Alaska might look different than leaves in Costa Rica. Homework: Revise your test. Science Starter: 1.Where do plants get energy from? 2.Where do animals get energy from? 3.Name one rainforest plant adaptation that you learned about from your plant packet.

Table Group Point! Where is Costa Rica?

Table Group Point! Who can guess what Ms. Petersen’s favorite flower is?

Table Group Point! Do trees have a stem? (You have to explain your answer.)

Table Group Point! 3 Tell me 3 things you know about leaves.

Function of leaves Leaves trap light energy for photosynthesis. Leaves produce sugar from photosynthesis Leaves exchange gases. Which gasses do leaves exchange? oxygen and carbon dioxide Which gas do leaves produce? oxygen

Leaf Structure Leaf Width: Wider leaves catch more light energy. Thin leaves help get carbon dioxide from bottom to top of leaf quickly for photosynthesis.

Pros and Cons of Big Leaves Pro of big leaves: Bigger leaves can do more photosynthesis Con of big leaves: Bigger leaves also lose more water through transpiration.

Pine trees live in places that are cold and dry. Costa Rica is a rainforest. It has wide-leaved plants. Why does that make sense?

Gas exchange Leaves are designed to let carbon dioxide to get to the layer of chlorophyll at the top of the leaf. They have small holes called stomata on the under surface.

Stomata – small openings in leaves that open and close at different times of the day to let in carbon dioxide and let oxygen out When it is light the plant needs CO 2 for photosynthesis so the stoma open. Stomata

Table Group Point! Would stomata be more likely to be open during the day or at night? (Be prepared to explain your answer.)

Stomata Carbon dioxide oxygen Guard cell Provided plant is photosynthesising

Stomata position

Guard Cells Stomata are surrounded by guard cells. Guard Cells – surround the stomata and control the size of the stomata’s opening to help prevent water loss.

Two Table Group Points! Think about the function of guard cells. Which structure of the eye are guard cells most like? (Be prepared to explain your answer.)

Guard Cells and Transpiration Transpiration – letting water vapor out through the stomata Transpiration cools the plant down (like sweating). Guard cells control transpiration.

Critical Thinking! What might happen if plants didn’t have guard cells or if the guard cells in a leaf weren’t working?

Leaf diagram – palisade layer CO 2 Most chlorophyll

Epidermis and Cuticle Just like humans have an epidermis, or skin, plants also have an epidermis. Epidermis – the outermost layer of a leaf

Leaf Cuticle Leaf Cuticle – waxy layer on the outside of the leaf that helps prevent water loss

Why would the waxiness help prevent water loss?