March 4, 2013Q-2 Pg. - PowerPoint PPT Presentation
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Title: March 4, 2013Q-2 Pg.
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March 4, 2013 Q-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
- Where do plants get energy from?
- Where do animals get energy from?
- Name one rainforest plant adaptation that you
learned about from your plant packet.
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Table Group Point!
Where is Costa Rica?
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Table Group Point!
Who can guess what Ms. Petersens favorite flower
is?
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Table Group Point!
Do trees have a stem? (You have to explain your
answer.)
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Table Group Point!
Tell me 3 things you know about leaves.
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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
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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.
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- 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.
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- 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?
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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.
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Stomata
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 CO2 for photosynthesis so
the stoma open.
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Table Group Point!
Would stomata be more likely to be open during
the day or at night? (Be prepared to explain your
answer.)
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Stomata
oxygen
Guard cell
Provided plant is photosynthesising
Carbon dioxide
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Stomata position
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Guard Cells
- Stomata are surrounded by guard cells.
- Guard Cells surround the stomata and control
the size of the stomatas opening to help prevent
water loss.
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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.)
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Guard Cells and Transpiration
- Transpiration letting water vapor out through
the stomata - Transpiration cools the plant down (like
sweating). - Guard cells control transpiration.
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Critical Thinking!
- What might happen if plants didnt have guard
cells or if the guard cells in a leaf werent
working?
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Leaf diagram palisade layer
Most chlorophyll
CO2
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Epidermis and Cuticle
- Just like humans have an epidermis, or skin,
plants also have an epidermis. - Epidermis the outermost layer of a leaf
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Leaf Cuticle
- Leaf Cuticle waxy layer on the outside of the
leaf that helps prevent water loss
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Why would the waxiness help prevent water loss?
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