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Questions and Answers
What is the primary process by which plants increase in cell number?
What is the primary process by which plants increase in cell number?
- Photosynthesis
- Cell differentiation
- Cell division by mitosis (correct)
- Cell elongation
Which of the following factors do plants respond to in their environment?
Which of the following factors do plants respond to in their environment?
- Light (correct)
- Sound
- Temperature
- Nutrients
What distinguishes plant growth from development?
What distinguishes plant growth from development?
- Growth is an increase in cell size or number. (correct)
- Growth involves changes in cell structure.
- Development occurs without mitosis.
- Development primarily involves mitotic division.
Which cell types are examples of specialized cells formed during plant development?
Which cell types are examples of specialized cells formed during plant development?
What is meant by 'cell elongation' in plant growth?
What is meant by 'cell elongation' in plant growth?
How do plants undergo development?
How do plants undergo development?
What is the expected average leaf length for acacias in the high browsing intensity location?
What is the expected average leaf length for acacias in the high browsing intensity location?
Which of the following characteristics is predicted to be highest in trees subjected to heavy browsing by giraffe?
Which of the following characteristics is predicted to be highest in trees subjected to heavy browsing by giraffe?
How does average spine length change with browsing intensity according to the predictions made in the study?
How does average spine length change with browsing intensity according to the predictions made in the study?
Which browsing intensity had the lowest average leaf width reported?
Which browsing intensity had the lowest average leaf width reported?
What was the average spine density for acacias in the medium browsing intensity location?
What was the average spine density for acacias in the medium browsing intensity location?
Which variable did NOT show a significant decrease in values as browsing intensity increased?
Which variable did NOT show a significant decrease in values as browsing intensity increased?
What is the average concentration of tannins found in acacias at the low browsing intensity site?
What is the average concentration of tannins found in acacias at the low browsing intensity site?
Which browsing intensity group had the highest average leaf density reported?
Which browsing intensity group had the highest average leaf density reported?
What type of light source was used in the experiment to observe phototropism?
What type of light source was used in the experiment to observe phototropism?
How did the plant in the experiment respond to the unilateral light?
How did the plant in the experiment respond to the unilateral light?
What was a key feature of the control setup in the experiment?
What was a key feature of the control setup in the experiment?
Which variable can be identified as dependent in this experiment?
Which variable can be identified as dependent in this experiment?
Which of the following components is part of the experimental setup that contributed to the plant's growth direction?
Which of the following components is part of the experimental setup that contributed to the plant's growth direction?
What does phototropism signify in plants?
What does phototropism signify in plants?
What phenomenon explains the plant's growth pattern in the experiment?
What phenomenon explains the plant's growth pattern in the experiment?
In terms of plant responses, which condition maintained by the clinostat in the control setup is crucial for comparison?
In terms of plant responses, which condition maintained by the clinostat in the control setup is crucial for comparison?
What is the primary role of gibberellins in plants?
What is the primary role of gibberellins in plants?
How do auxins influence tropic responses in plants?
How do auxins influence tropic responses in plants?
What effect does abscisic acid have on seeds?
What effect does abscisic acid have on seeds?
Which process is primarily influenced by phototropism?
Which process is primarily influenced by phototropism?
What happens to auxin production under normal conditions in a plant?
What happens to auxin production under normal conditions in a plant?
What is a negative tropic response?
What is a negative tropic response?
Which plant hormone inhibits root and shoot growth?
Which plant hormone inhibits root and shoot growth?
How does gibberellins affect mature leaves during fruit development?
How does gibberellins affect mature leaves during fruit development?
Which function is associated with Auxins?
Which function is associated with Auxins?
Where are Auxins primarily found in plants?
Where are Auxins primarily found in plants?
What is a characteristic of plant hormones compared to animal hormones?
What is a characteristic of plant hormones compared to animal hormones?
What process do Auxins mainly control in plants?
What process do Auxins mainly control in plants?
Which function is NOT associated with Gibberellins?
Which function is NOT associated with Gibberellins?
What is the role of Abscisic Acid (ABA) in plants?
What is the role of Abscisic Acid (ABA) in plants?
What does apical dominance refer to?
What does apical dominance refer to?
What is the primary role of plant hormones?
What is the primary role of plant hormones?
Study Notes
Plant Responses to the Environment
- Plants react to environmental stimuli such as light, water, gravity, and touch.
- They utilize growth patterns instead of locomotion to respond.
- Growth vs. Development: Growth is an increase in cell number and size; Development is the differentiation of meristematic cells into specialized cells.
Plant Hormones/Growth Substances
- Hormones: Chemical substances produced in small amounts in one body part and cause responses in another.
- Plant hormones, or growth substances, act in the organ of production, unlike animal hormones, which are transported via blood.
- Five main groups of plant hormones, focusing on Auxins, Gibberellins, and Abscisic Acid (ABA).
Functions of Key Plant Hormones
-
Auxins:
- Produced in actively growing regions (meristems) like new leaves and root tips.
- Promote cell elongation behind the shoot and root tip.
- Inhibit lateral bud development (apical dominance).
- Control tropic movements and fruit development.
- Prevent leaf abscission.
-
Gibberellins:
- Found in young leaves, developing seeds, and fruits.
- Stimulate growth via cell elongation, particularly in stems.
- Promote seed germination, cell division in meristems, and development of flowers and fruits.
-
Abscisic Acid (ABA):
- Present in roots, mature leaves, fruits, and terminal buds.
- Inhibits seed germination and root/shoot growth.
- Promotes abscission of ripe fruit and leaves, and winter dormancy in plants.
Auxins and Tropic Responses
- Tropic movements are plant growth responses to external stimuli, influenced by uneven distribution of auxins.
- Positive tropism: Growth toward a stimulus (e.g., light).
- Negative tropism: Growth away from a stimulus (e.g., gravity).
Auxins in Phototropism
- Under unilateral light, auxins distribute unevenly, resulting in greater elongation on the light-facing side, causing the plant to bend toward the light source.
- Control experiments with equal light exposure result in straight growth.
Case Study: Paperbark Acacias and Giraffe Browsing
- Acacia trees are a key food source for giraffes and are nutritionally richer than many other trees.
- Three browsing intensity sites were studied: low, medium, high.
- Observations included:
- Average leaf lengths decrease with increased browsing intensity.
- Average leaf widths also decrease with increased browsing.
- Leaf density shows minor variations among groupings.
- Spine density increases with browsing intensity, while spine length is longest in heavily browsed areas.
- Tannin concentration varies, with no clear trend linked to browsing intensity.
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Description
This quiz covers how plants respond to environmental stimuli and the role of hormones in growth and development. Focus is given to key plant hormones like Auxins, Gibberellins, and Abscisic Acid, along with their functions and effects on plant behavior. Test your understanding of these crucial biological processes.
