Chapter 9 Flashcards
(23 cards)
Describe the difference between the functioning of unicellular and multicellular organisms.
Unicellular organisms have one cell that performs all functions. Multicellular organisms have many specialized cells that perform specific tasks.
What is photosynthesis?
Biochemical process powered by light energy in which CO2 from the air and H2O from the soil combine to create glucose.
What is glucose?
Carbohydrate used by both animal and plant cells as a source of energy.
What is a byproduct of photosynthesis?
Oxygen gas.
What is the formula for photosynthesis?
6CO2 + 6H2O + light energy = C6H12O6 + 6O2
What is the formula for cellular respiration?
C6H12O6 + 6O2 = 6CO2 + 6H2O (photosynthesis but reversed)
Most photosynthesis occurs in the ______ of a plant.
leaves
What is chlorophyll?
A pigment molecule found in chloroplasts that traps light energy.
Epidermal cells
Protect the leaf (no chloroplasts). Mostly transparent to allow the entry of solar energy. Covered by the cuticle, a waxy substance that prevents water evaporation.
Epidermis (made up of epidermal cells)
Tightly knit, one cell thick sheet found on the upper and lower surfaces of the leaf.
Palisade tissue cells
Long, narrow cells that are packed closely together. Found just under the leaf’s upper surface, where they are exposed to sunlight. Packed w/ chloroplasts. Their shape + organization is ideal for photosynthesis and is where most of it occurs.
Spongy tissue cells
Also contain chloroplasts. They are round, loosely packed, and contain many air spaces in between. Their structure is ideal for gas and water exchange with the environment.
Stomata
Small openings in the epidermis that allow gases in and out of the leaf. CO2 in, O2 out. Also where water vapour diffuses out of the leaf. Mostly found on the underside of leaf.
Guard cells.
Regulate the size of the stomata by changing shape. Each stoma is flanked by two guard cells.
Vascular tissue cells
Form a series of tubes that transport fluids up and down the plant. The xylem takes water and minerals up from the roots and the phloem takes sugars down from the leaves.
What are the air spaces in between cells inside leaves used for?
Gases circulate in and out of these intercellular spaces by passive transport.
Explain the process of gas exchange in leaves.
Air enters through the stomata by diffusion. It then circulates in the air spaces in between cells. CO2 diffuses with passive transport, dissolving into the watery films of cells and eventually the cells themselves. It is then used by chloroplasts for photosynthesis. O2 produced during photosynthesis passes out of the cells into the air spaces, diffuses through the stomata, and goes into the air.
Lenticels
Lens-shaped openings that perforate the bark of woody plants and that enable the root and stem cells of trees to exchange gases w/ the environment.
Transpiration
The evaporation of water from leaves.
_______ of photosynthesis are possible when the stomata are open
High rates
_______ of photosynthesis are possible when the stomata are closed.
Low rates
Explain how the opening and closing of the stomata affect transpiration.
When water enters the leaf by osmosis, the turgor pressure inside guard cells increases, causing them to swell and opening the stomata. Transpiration occurs, causing water loss. The amount of water in the guard cells thus decreases and the stomata close until more water enters to force them open again.
What is the job of the xylem tissue?
To transport water and dissolved minerals from the roots throughout the plant.
