Plant transport, storage and gas exchange Flashcards
Plants make their own food meaning they are
Autotrophic
Plants transport
Water, Carbon dioxide, oxygen, minerals and plant growth regulators for metabolism
Why is water needed
Photosynthesis, cell metabolism, growth and cell turgidity
Water uptake by roots
- Water is absorbed by root hairs by osmosis
- Water enters the cytoplasm
- Water moves from cell to cell by osmosis
How are root hairs adapted
- Provide a large surface area
- No cuticle
- Have thin walls
What is the transport of water caused by
- Root pressure
2. Transpiration
Root pressure
forced upward movement of water and minerals from the root to stem
Transpiration
Loss of water vapour from a plant through stomata
Cohesion-Tension theory
- Water evaporates at the leaf in transpiration
- Loss of water creates tension
- Tension pulls water up as a continuous stream creating a transpiration stream
- Water molecules are attracted to each other in a process called cohesion
- Water molecules are attracted to the xylem in a process called adhesion
- Root pressure is a force generated by the root, as water is absorbed, it pushes water up the stem
Name 2 scientists associated with the cohesion-tension model of transport
- Dixon
- Joly
Mineral uptake and transport
- Minerals are absorbed into the root hairs by active transport
- Passed through xylem and carried up the stem
- Root hair cells are adapted as mitochondria supplies energy
- Minerals needed are calcium(forms middle lamella) and magnesium (produce chlorophyll)
Carbon dioxide uptake and transport
- CO2 diffuses in through the stomata of the leaf from the atmosphere
- Respiration in plant cells provides CO2 to the plant
- CO2 diffuses through the air spaces in the leaf to the ground tissue or mesophyll cells
Transport and Oxygen
- O2 is a product of photosynthesis
- Some O2 is used in plant respiration and excess O2 diffuses into the atmosphere through the stomata
Transport of the photosynthetic product glucose
- Translocated as sucrose in phloem sieve tubes
- Sucrose is the main transport carbohydrate in phloem
Transport of growth regulators
- Diffusion and active transport
Modified root
- Taproot
- Carrots
- Glucose
Modified stem
- Potato tuber
- Starch
Modified leaf
- Bulb is an underground stem with leaves
- Onions
- Glucose
Perennials
Plants that survive from one growing season to the next by storing food as starch
Gas exchange through leaf stomata
- Stomata are dermal pores/openings for gas exchange
- CO2 diffuses through stomata from the atmosphere
- O2 diffuses out through stomata into the atmosphere
- Water vapour moves out from stomata called transpiration
How is the leaf adapted
- A large number of stomata
- Thin
- Increase surface area
Control of transpiration
- Waxy cuticle is waterproof
- Closure of stomata in times of water shortage
Name the structures found in stems
Lenticels
Name two compounds that leave the plant through the lenticels
- water
- oxygen
Define lenticels
- Openings in the stem which allow gas exchange
Factors that control stomatal opening and closing
- Water- open when guard cells become turgid
2. CO2- no photosynthesis at night since no light but photosynthesis resumes in the morning
Indicate 2 ways plants use to control transpiration
- Waxy cuticle is waterproof
- closure of stomata
Give 2 structural differences between Xylem and Phloem
- Phloem has nuclei xylem doesn’t
- Xylem is a continuous tube and phloem is not
Name the vascular tissue through which the products of photosynthesis are transported in plants
Phloem
Give 2 structural features of Phloem
- Sieve tube
- Companion cells
Describe the relationship between the rate of transpiration and the rate of water uptake during the day
Name a reason why
- Water uptake and rate of transpiration increases
- More water absorption to replace the water lost
Under what conditions does the highest rate of transpiration occur on the day
- Higher temperature
- Bright conditions
Name the cells which control the opening and closing of stomata
Guard cells
What is the advantage to plants having most of their stomata on the underside of the leaf
Reduce water loss by transpiration
Give a disadvantage to plants of a high rate of transpiration
Wilting
What do plants do in response to wilting
Close stomata
Name 2 Irish scientists who proposed the theory of water movement in plants
Dixon and Joly
Name the openings in the leaf which allow the entry of carbon dioxide for photosynthesis
Stomata
Factors that influence the diameter of these openings
CO2
Distinguish between Tuber and Bulb
Tuber - stem
Bulb - Leaf
What is the function of stomata
Gas exchange
Name a factor in stems equivalent to stomata
Lenticels
Name a plant in which the leaves are modified for food storage
Onions
Name a carbohydrate that you would expect to find in the modified leaves
Starch
Name a type of modified stem that functions in food storage
Potato tuber
Name a type of modified root that functions in food storage
Carrot
