B2 - Organisms in the Environment Flashcards
What colours of light are most useful in photosynthesis?
Red, yellow and violet
What is the definition of variegated?
Uneven distribution of chloroplasts in the leaf cells.
Why can life survive despite inefficiency in energy conversions?
The sun continually provides new energy.
Where do the light reactions of photosynthesis take place?
Thylakoids
Why do plants contain mitochondria as well as chloroplasts?
Plants must make use of respiration when light is not available.
Where does photosynthesis take place?
The chloroplast
What part of the cell captures sunlight?
The chloroplasts
Why do plants change colour in autumn?
- Shut down chlorophyll
* Turn on carotenoids
What are the protective layers of the chloroplast?
The outer and inner membranes
How do plants get the water they need for photosynthesis?
Through the roots
True of false:
Photosynthesis occurs only in the day
False
What are leaves?
Special organ of a plant adapted for catching and absorbing sunlight
What are carotenoids?
Pigment in chloroplasts that absorbs sunlight and reflects colours other than green
Where does energy for photosynthesis come from?
Sunlight
Where are the pigment molecules responsible for photosynthesis located?
The stroma of the chloroplasts
What is a limiting factor?
A value which is in the shortest supply, stopping photosynthesis from occurring faster.
What are the effects of optimising the growing conditions?
- Plants grow faster
- Fruit earlier
- Give higher yields
What are three ways in which farmers optimise plant growth?
- Polytunnels
- Full greenhouses
- Hydroponics
Why is glucose useful in a plant?
It forms the basis for all organic compounds within a plant.
What are three uses of glucose?
- Joined together to form starch for storage
- Used for respiration for energy
- Builds cellulose for cell walls
Why can’t glucose be used as a storage molecule?
Glucose is soluble and affects the movement of water in the cell.
