B6 Plant Structures and their Functions Flashcards
What is the word equation for photosynthesis?
Carbon dioxide + water —> glucose + oxygen
What are the three factors affecting the rate of photosynthesis?
- Carbon dioxide concentration
- Light intensity
- Temperature
What is the function of root hair cells?
They take in mineral ions by active transport and water by osmosis
What are the adaptations of root hair cells?
Large surface area to absorb water and mineral ions
What is the function of phloem tubes?
Transport sugars to the rest of the plant (translocation)
What are the adaptations of phloem tubes?
Made of elongated living cells with pores in the end walls to allow for the flow of substances
What is the function of xylem tubes?
They carry water and mineral ions from the roots to the leaves
What are the adaptations of xylem tubes?
Made of dead cells joined end to end with no cell walls. They are strengthened by lignin
What is transpiration?
Where water evaporates and diffuses out of the leaves
What is the role of guard cells?
They are pores on the bottom of leaves that control the size of the pore
How do guard cells work?
When turgid, the stomata are open and when flaccid, the stomata are closed
How does light intensity affect transpiration rate?
The brighter the light, the greater the transpiration rate. Stomata begin to close when it gets darker as photosynthesis doesn’t occur in the dark so they don’t need to be open to let in CO2
How does temperature affect transpiration rate?
The warmer it is, the faster transpiration occurs as the particles have more energy to evaporate and diffuse out of the stomata
How does airflow affect transpiration rate?
The better the air flow, the greater the transpiration rate as there is a larger concentration gradient so more diffusion occurs
What are some adaptations of plants to live in extreme environments?
- Small leaves to reduce transpiration
- Spines to stop animals eating the plant to get water
- Thick waxy cuticles to reduce water loss
- Thick stem to store water
What is the function of auxins?
They promote growth in shoots but inhibit growth in roots
How are auxins used commercially?
- Weedkillers - Auxins get sprayed, which only affect broad-leaved plants and disrupts their growth patterns, killing them
- Growing cuttings with rooting powder - rooting powder containing auxins can be added to cuttings which rapidly start growing
How are gibberellins used commercially?
- Controlling flower and fruit formation - Stimulate seed germination and make plants flower earlier. They can also reduce flower formation, improving fruit quality
- Producing seedless fruit - If added to unpollinated flowers, the fruit would grow but the seeds won’t
- Controlling seed germination - Can make plants germinate at all times of the year
How is ethene used commercially?
- Controlling the ripening of fruits - Can ripen fruits
