Untitled Deck Flashcards
(14 cards)
What are heterotrophs?
Obtain food by feeding on other organisms
Heterotrophs cannot produce their own food and rely on other organisms for sustenance.
What are autotrophs?
Make food by photosynthesis
Autotrophs can produce their own food using light energy, typically through the process of photosynthesis.
Define photosynthesis.
An anabolic process in which complex organic molecules are formed from simple inorganic molecules using light energy
Photosynthesis is essential for converting light energy into chemical energy stored in glucose.
What are the products of photosynthesis?
- Glucose
- Water
- Oxygen
Glucose is used in respiration, water is reused or exits as vapor, and oxygen is a by-product released into the atmosphere.
What is the function of the cuticle in plants?
A waxy, water-proof layer that reduces water loss by transpiration
The cuticle also allows sunlight to pass through for photosynthesis.
Describe the upper epidermis of a leaf.
- Made of a single layer of epidermal cells
- Do not have chloroplasts
- Protects inner layers of cells
- Covered by cuticle
The upper epidermis is transparent to allow sunlight to reach the chloroplasts below.
What are palisade mesophyll cells?
- Very closely packed
- Contain a large number of chloroplasts
- Main site of photosynthesis
- Located just below the upper epidermis
These cells are optimized for maximum light absorption.
What characterizes spongy mesophyll cells?
- Irregular in shape
- Loosely packed
- Contain less chloroplasts
- Allow gas circulation with air spaces
- Covered with a layer of moisture
Spongy mesophyll cells facilitate gas exchange and support photosynthesis, albeit less efficiently than palisade cells.
What controls the opening and closing of stomata?
A pair of guard cells
The turgidity of guard cells determines whether the stomata are open or closed.
What happens to stomata when guard cells are turgid?
Stoma opens
Turgid guard cells swell, allowing gas exchange to occur.
What happens to stomata when guard cells are flaccid?
Stoma closes
Flaccid guard cells shrink, preventing gas exchange and minimizing water loss.
Where are stomata located in land plants?
On the underside of their leaves
This adaptation helps reduce water loss due to direct sunlight.
Where are stomata found in floating aquatic plants?
On the upper surface of their leaves only
These plants have stomata and cuticle on the upper side to facilitate gas exchange in water.
Describe the lower epidermis of a leaf.
- Made of a single layer of epidermal cells
- Do not have chloroplasts, EXCEPT FOR guard cells
- Covered by cuticle, usually thinner
The lower epidermis has a reduced risk of water loss due to its position.
