W10 Ch.34 Definitions

Question 1

Apical Meristem

Answer 1

This is the region of actively dividing cells found at the tips of roots and shoots in plants. It is responsible for the growth in length of the plant body

Question 2

Axillary Buds

Answer 2

These are buds found in the axil of a leaf, which is the angle formed between the upper side of the stem and the stem itself. These buds have the potential to form lateral shoots (branches) or flowers.

Question 3

Polar Transport

Answer 3

In plants, this refers to the movement of substances such as hormones, nutrients, or ions in a specific direction, typically from one end of the plant to the other. This transport is often controlled by concentration gradients or specific cellular mechanisms.

Question 4

Apical Dominance

Answer 4

This is a phenomenon where the growth of the main, central stem of a plant inhibits the growth of lateral branches or shoots. It’s primarily regulated by the hormone auxin.

Question 5

Gravitropism

Answer 5

Also known as geotropism, this is the growth response of plants to gravity. Roots typically exhibit positive gravitropism (growing towards gravity), while shoots exhibit negative gravitropism (growing away from gravity).

Question 6

Statolith

Answer 6

In plants, these are specialized organelles (such as starch-filled plastids) that settle in response to gravity, allowing the plant to detect its orientation and adjust its growth accordingly.

Question 7

Phototropism

Answer 7

This is the growth response of plants to light. Positive phototropism occurs when plants grow towards a light source, while negative phototropism (or skototropism) occurs when they grow away from it

Question 8

Phytochrome

Answer 8

This is a photoreceptor pigment found in plants that is sensitive to red and far-red light. It plays a key role in various plant processes, including seed germination, shade avoidance, and flowering

Question 9

Hypersensitive Response

Answer 9

This is a defense mechanism in plants against pathogens, typically involving rapid cell death at the site of infection to limit the spread of the pathogen

Question 10

Systemic Acquired Resistance (SAR)

Answer 10

This is a defense response in plants that occurs following an initial infection, resulting in enhanced resistance to subsequent infections throughout the plant

Question 11

Hormone

Answer 11

In plants, hormones are signaling molecules that regulate various physiological processes, including growth, development, and responses to environmental stimuli.

Question 12

Auxin

Answer 12

This is a class of plant hormones that regulate various aspects of plant growth and development, including cell elongation, apical dominance, and tropic responses (such as phototropism and gravitropism)

Question 13

Cytokinin

Answer 13

Cytokinins are a class of plant hormones that promote cell division and growth, delay senescence (aging) of tissues, and have roles in various physiological processes like nutrient mobilization and stress responses

Question 14

R Genes

Answer 14

R genes, or resistance genes, are genes in plants that provide resistance against pathogens such as bacteria, fungi, viruses, and nematodes. They encode proteins that recognize specific pathogen molecules and trigger defense responses in the plant

Question 15

Gibberellin Acid

Answer 15

Gibberellins are a class of plant hormones that regulate various aspects of plant growth and development, including stem elongation, seed germination, and flowering.

Question 16

Gibberellic Acid

Answer 16

Gibberellic acid is a specific type of gibberellin, a plant hormone that regulates growth and development, particularly stem elongation and seed germination.

Question 17

Abscisic Acid

Answer 17

Abscisic acid is a plant hormone that plays a key role in seed dormancy, drought tolerance, and stress responses. It inhibits growth and promotes stomatal closure to reduce water loss

Question 18

Ethylene

Answer 18

Ethylene is a gaseous plant hormone involved in various physiological processes, including fruit ripening, senescence, and response to stress. It regulates processes such as fruit ripening, leaf abscission, and flower senescence

Question 19

Photoperiodism

Answer 19

Photoperiodism is the response of an organism to the length of day and night. In plants, it influences processes such as flowering, dormancy, and leaf senescence.

Question 20

Circadian Rhythm

Answer 20

Circadian rhythm refers to the 24-hour biological cycle that regulates various physiological processes in organisms, including plants. It controls processes such as leaf movement, flowering time, and metabolic activities

Question 21

Vernalization

Answer 21

Vernalization is the process by which certain plants require exposure to a period of cold temperature to induce or accelerate flowering. It prevents premature flowering and ensures synchronization with favorable growing conditions

Question 22

Dormancy

Answer 22

Dormancy is a state of reduced metabolic activity in plants, typically triggered by environmental factors such as temperature or photoperiod. It allows plants to survive unfavorable conditions and resume growth when conditions become favorable.

Question 23

Gravitropism

Answer 23

Gravitropism, also known as geotropism, is the growth response of plants to gravity. It causes roots to grow downward (positive gravitropism) and shoots to grow upward (negative gravitropism)

Question 24

Tropism

Answer 24

Tropism is the growth or movement of an organism in response to an external stimulus, such as light (phototropism), gravity (gravitropism), or touch (thigmotropism)

Question 25

Heliotropism

Answer 25

Heliotropism is the movement or growth of a plant in response to sunlight, typically involving the movement of leaves or flowers to track the sun’s position

Question 26

Bolting

Answer 26

Bolting is the rapid elongation of the flowering stem of certain plants, often in response to environmental cues such as increased temperature or photoperiod. It is commonly observed in biennial or perennial plants as they transition to the reproductive phase

Question 27

Abscission

Answer 27

Abscission is the shedding of leaves, flowers, fruits, or other plant organs, typically as a natural process or in response to environmental cues such as senescence or stress

Question 28

Nastic Movement

Answer 28

Nastic movement is a non-directional response of plant organs to external stimuli, such as touch or temperature changes, that does not depend on the direction of the stimulus

Question 29

Photomorphogenesis

Answer 29

Photomorphogenesis is the developmental processes in plants that are influenced by light, including seed germination, seedling growth, and chlorophyll synthesis

Question 30

Phenotypic Plasticity

Answer 30

Phenotypic plasticity refers to the ability of a single genotype to produce different phenotypes in response to different environmental conditions

Question 31

Abscission Zone

Answer 31

The abscission zone is a specialized region in plants where cells undergo programmed cell death, leading to the detachment of leaves, flowers, or fruits

Question 32

Acid-Growth Hypothesis

Answer 32

The acid-growth hypothesis proposes that cell elongation in plants is mediated by the acidification of the cell wall, which loosens the cell wall structure, allowing for increased cell expansion

Question 33

Phototropin

Answer 33

Phototropins are blue-light photoreceptor proteins found in plants that mediate various light responses, including phototropism, chloroplast movement, and stomatal opening

Question 34

Cryptochrome

Answer 34

Cryptochromes are blue-light photoreceptor proteins found in plants and animals that regulate various biological processes, including circadian rhythms, photomorphogenesis, and flowering

Question 35

Thigmotropism

Answer 35

Thigmotropism is the growth response of plants to touch or mechanical stimulation. It causes plant organs to bend or grow in response to contact with solid objects

Question 36

Secondary Metabolites

Answer 36

Secondary metabolites are organic compounds produced by plants that are not directly involved in growth, development, or reproduction. They often have specialized functions such as defense against herbivores, attraction of pollinators, or allelopathy

Question 37

Second-Messenger Systems

Answer 37

Second-messenger systems are signaling pathways in cells that transmit extracellular signals to intracellular targets, often involving the production or release of small molecules (second messengers) such as cyclic AMP or calcium ions

Question 38

Thigmomorphogenesis

Answer 38

Thigmomorphogenesis is the developmental response of plants to mechanical stimulation, resulting in changes in morphology, physiology, and gene expression. It often involves adaptations to wind or touch

Question 39

Alkaloid

Answer 39

Alkaloids are a class of nitrogen-containing organic compounds produced by plants, often with pharmacological effects on animals. They have diverse biological activities and are found in many medicinal and toxic plants. Examples include caffeine, nicotine, and morphine.