Plant Hormones Flashcards
Homeostasis and Response (14 cards)
What is auxin?
Auxin is a plant hormone that controls growth near the tips of shoots and roots.
Auxin plays a crucial role in regulating plant growth and development.
In response to what two factors does auxin control plant growth?
Auxin controls growth in response to light (phototropism) and gravity (geotropism).
Phototropism refers to the growth of plants toward light, while geotropism refers to growth in response to gravity.
Where is auxin produced in a plant?
Auxin is produced in the tips of shoots and roots.
This production is essential for the growth and elongation of plant cells.
What happens if the tip of a shoot is removed?
If the tip of a shoot is removed, no auxin is available, and the shoot may stop growing.
This demonstrates the importance of auxin in sustaining plant growth.
How does auxin affect growth in shoots and roots?
Excess auxin promotes growth in shoots but inhibits growth in roots.
This differential effect helps direct plant growth towards light and downwards into the soil.
What occurs when a shoot tip is exposed to light?
More auxin accumulates on the shaded side, causing the cells there to elongate faster, bending the shoot toward the light.
This is a key mechanism of phototropism.
What happens to a shoot growing sideways due to gravity?
Gravity causes an unequal distribution of auxin, with more auxin on the lower side, leading to faster growth on that side and bending the shoot upwards.
This response is known as geotropism.
How does auxin affect a root growing sideways?
In a root, excess auxin inhibits growth, causing the cells on top to elongate faster and the root to bend downwards.
This is the opposite effect of auxin in shoots.
What is a practical way to investigate the effect of light on plant growth?
Put 10 cress seeds into three Petri dishes, shine a light onto one from above and two from different directions, then observe their responses after one week.
This experiment demonstrates phototropism in cress seedlings.
What is an important variable to control in plant growth experiments?
The number of seeds used.
Consistency in the number of seeds ensures that results are due to the experimental conditions rather than variations in seed quantity.
How can you control the type of seed in an experiment?
Use seeds that all come from the same packet.
This ensures genetic consistency among the seeds being tested.
What should be done to control temperature in plant growth experiments?
Keep the Petri dishes in a stable temperature environment, away from heat sources and drafts.
Temperature fluctuations can affect plant growth and skew results.
How can water be controlled in a plant growth experiment?
Use a measuring cylinder to add the same amount of water to each dish.
Consistent watering is crucial for fair testing in plant growth experiments.
What should be done to control light intensity in an experiment?
Keep the distance between the light bulb and dish the same.
Variations in light intensity can lead to differences in plant growth responses.
