Leaves Flashcards
Why to leaves have a large surface area?
To absorb light rays
Why do they have a thin shape?
So gases can diffuse in and out quickly.
Why do they have green chlorophyll?
To absorb light
Why do leaves have veins?
To support the leaf surface and to carry substances to and from all the cells in the leaf.
What is the cuticle?
Waterproof layer that also cuts down the water lost by evaporation.
What is the upper epidermis?
Single layer of cells with no chloroplasts. Light goes straight through.
What is the palisade layer?
The palisade cell contains lots of chloroplasts. Most photosynthesis occurs here.
What is the vein?
Contains tubes called xylem that bring water and salts to the leaf and tubes called phloem that take dissolved food away.
What is the spongy layer?
More rounded cells with lots of air spaces between them, gaseous exchange occurs here.
What is the lower epidermis?
No thick cuticle. Has lots of tiny pores called stomata (singular stoma) . These allow gases to diffuse in and out.
What are stomata?
Small pores on the underside of the leaf that let gases diffuse in and out.
________ diffuse in for photosynthesis. _____ made in photosynthesis diffuses out. Water _____ diffuses out.
Carbon dioxide
Oxygen
Vapor
Why are stomata in the underside of the leaf?
Stomata are present on the lower epidermis to reduce the loss of water by evaporation as less sunlight falls on the lower epidermis.
How can stomata be opened and closed?
By guard cells
When do stomata usually open?
During the day
How does water pass into the guard cells?
Osmosis. This makes them bend so the stoma opens. Carbon dioxide diffuses into the leaf for photosynthesis.
The stomata close at _____. Water passes out of the cells by _______. They ______ up so the so the stoma closes.
Night
Osmosis
Straighten
Why do stomata close during hot weather ?
In many plants, when the outside temperature is warm and water evaporates more readily, plants close their stomata to prevent excessive water loss.
What do plants need to do for respiration?
Take in oxygen and give out carbon dioxide. Respiration takes place all the time.
What to plants need to happen for photosynthesis which is opposite to respiration?
Take in carbon dioxide and give out oxygen. Photosynthesis only takes place in the light.
The gases pass into and out of leaves through the _____.
Stomata
Why do we have plant food on sale?
Plants need mineral salts or nutrients.
Why do plants need nitrates?
Need the nitrogen to make proteins. So nitrogen is one nutrient needed for growth.
What is magnesium used for in plants?
To make chlorophyll. Leaves without magnesium look yellow. We say the plant is deficient in magnesium.
During daylight plants produce more oxygen by ____ than they use in _______. At night plants produce only _______ by respiration.
Photosynthesis
Respiration
Carbon dioxide
How can you tell a plant lacks nitrate?
Stunted growth and yellow older leaves
How can you tell a plant lacks phosphate?
Poor root growth and purple younger leaves.
How can you tell a plant lacks potassium?
Yellow leaves with dead spots.
Adaption of epidermis:
Epidermal cells are transparent with no chloroplasts so light goes through
Why does the leaf have vascular bundles?
For water (xylem) and food (phloem)
What is stomata used for?
Gas exchange
Adaptation of palisade mesophyll:
Many chloroplasts for photosynthesis
Adaptation of spongy mesophyll:
More rounded with lots of air spaces to make gas exchange easier.
What are parenchyma cells?
Thin-walled cells that make up the inside of many non-woody plant structures including stems, roots and leaves.
What is the function of parenchyma?(3)
Healing & Repair
Photosynthesis
Nutrient and food storage
What is collenchyma?
Tissue strengthened by the thickening of cell walls.
What is the function of collenchyma?
Enable additional support to the areas they are found.
