Gas Exchange & Transport Systems (PPT 7-10) (U1) Flashcards
What are the two energy transforming processes in plants?
- Respiration
- Photosynthesis
Explain the relationship between photosynthesis and the main tissues of leaves?
- The organ incorporates a variety of different tissues to enable photosynthetic cells to get energy.
- Leaves are constructed to maximise light, capture carbon dioxide and minimise water loss.
How do leaves maximise light capture?
- They are broad to provide large surface area.
- Are positioned in such a way to maximise exposure.
How do leaves minimise water loss?
- Leaves are held out from the stalk by a petiole.
- Some plants can tilt their leaves.
Why are there veins in leaves?
To transport the reactants and products of photosynthesis.
Why are plant leaves so thin?
- So that light penetrates to all photosynthetic cells.
- Provide a short diffusion distance for carbon dioxide.
What is the epidermis?
A single transparent layer of cells that protect the leaf, but allow light to pass through. A requirement for photosynthesis.
What is the structure and function of the palisade mesophyll?
S- Located under the upper epidermis. Consists of closely packed cells that contain chloroplasts.
F- The site of photosynthesis due to the high concentration of chloroplasts.
What is the structure and function of the spongy mesophyll?
S- Are a loosely packed layer of more rounded cells, with large air spaces for easy air and water.
F- Structured to facilitate water and gas transport required for photosynthesis.
What is the structure and function of xylem tissue?
S- A series of hollow pipes heavily strengthened by a substance called lignin.
F- Carrying water & dissolved mineral ions required for photosynthesis.
What is the structure and function of sieve tubes and companion cells?
S- Series of cells laid end to end with sieve plates that allow sugars pass.
Companion cells sit adjacent to sieve tubes.
F- Carry organic solutes (sugars) that are the product of photosynthesis.
