Questions and Answers
What is the primary process by which plants increase in cell number?
Which of the following factors do plants respond to in their environment?
What distinguishes plant growth from development?
Which cell types are examples of specialized cells formed during plant development?
Signup and view all the answers
What is meant by 'cell elongation' in plant growth?
Signup and view all the answers
How do plants undergo development?
Signup and view all the answers
What is the expected average leaf length for acacias in the high browsing intensity location?
Signup and view all the answers
Which of the following characteristics is predicted to be highest in trees subjected to heavy browsing by giraffe?
Signup and view all the answers
How does average spine length change with browsing intensity according to the predictions made in the study?
Signup and view all the answers
Which browsing intensity had the lowest average leaf width reported?
Signup and view all the answers
What was the average spine density for acacias in the medium browsing intensity location?
Signup and view all the answers
Which variable did NOT show a significant decrease in values as browsing intensity increased?
Signup and view all the answers
What is the average concentration of tannins found in acacias at the low browsing intensity site?
Signup and view all the answers
Which browsing intensity group had the highest average leaf density reported?
Signup and view all the answers
What type of light source was used in the experiment to observe phototropism?
Signup and view all the answers
How did the plant in the experiment respond to the unilateral light?
Signup and view all the answers
What was a key feature of the control setup in the experiment?
Signup and view all the answers
Which variable can be identified as dependent in this experiment?
Signup and view all the answers
Which of the following components is part of the experimental setup that contributed to the plant's growth direction?
Signup and view all the answers
What does phototropism signify in plants?
Signup and view all the answers
What phenomenon explains the plant's growth pattern in the experiment?
Signup and view all the answers
In terms of plant responses, which condition maintained by the clinostat in the control setup is crucial for comparison?
Signup and view all the answers
What is the primary role of gibberellins in plants?
Signup and view all the answers
How do auxins influence tropic responses in plants?
Signup and view all the answers
What effect does abscisic acid have on seeds?
Signup and view all the answers
Which process is primarily influenced by phototropism?
Signup and view all the answers
What happens to auxin production under normal conditions in a plant?
Signup and view all the answers
What is a negative tropic response?
Signup and view all the answers
Which plant hormone inhibits root and shoot growth?
Signup and view all the answers
How does gibberellins affect mature leaves during fruit development?
Signup and view all the answers
Which function is associated with Auxins?
Signup and view all the answers
Where are Auxins primarily found in plants?
Signup and view all the answers
What is a characteristic of plant hormones compared to animal hormones?
Signup and view all the answers
What process do Auxins mainly control in plants?
Signup and view all the answers
Which function is NOT associated with Gibberellins?
Signup and view all the answers
What is the role of Abscisic Acid (ABA) in plants?
Signup and view all the answers
What does apical dominance refer to?
Signup and view all the answers
What is the primary role of plant hormones?
Signup and view all the answers
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.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
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.
