Plant Growth and Development Questions and Answers AP Inter 1st Year Botany Chapter 10

Andhra Pradesh BIEAP AP Inter 1st Year Botany Study Material 10th Lesson Plant Growth and Development Class 11 Textbook Exercise Questions and Answers.

Plant Growth and Development Class 11 Questions and Answers AP Inter 1st Year Botany 10th Lesson

I. Plant Growth and Development Multiple Choice Questions (1 Mark)

Question 1.
The three phases of growth in correct order is ………………
(1) meristematic, maturation, elongation
(2) elongation, meristematic, maturation
(3) meristematic, elongation, maturation
(4) elongation, maturation, meristematic
Answer:
(3) meristematic, elongation, maturation

Question 2.
The phase in which maximum growth can be seen in sigmoid curve.
(1) log
(2) lag
(3) stationary
(4) lag and log
Answer:
(1) log

Question 3.
An aquatic plant which shows plasticity ?
(1) Cotton
(2) Coriander
(3) Buttercup
(4) Larkspur
Answer:
(3) Buttercup

Question 4.
An example of adenine derivative plant growth regulator is ………………
(1) IAA
(2) Kinetin
(3) ABA
(4) Gibberellic acid
Answer:
(2) Kinetin

Question 5.
Gibberellic acid is ………………
(1) indole compound
(2) adenine compound
(3) carotenoid derivative
(4) terpene derivative
Answer:
(4) terpene derivative

Question 6.
The foolish seedling disease of rice is caused by ………………
(1) nematode
(2) bacteria
(3) fungus
(4) virus
Answer:
(3) fungus

Question 7.
2,4-D is used to kill …………..
(1) gymnosperms
(2) dicot weeds
(3) monocot grasses
(4) pteridophytes
Answer:
(2) dicot weeds

Question 8.
Bolting is …………..
(1) yellowing of leaves
(2) inter nodal elongation prior to flowering
(3) early seed production
(4) re greening of leaves
Answer:
(2) inter nodal elongation prior to flowering

Question 9.
Cytokinins help to produce …………..
(1) chloroplast in leaves
(2) stem elongation in sugarcane
(3) synchronized fruit set in pineapple
(4) flowering in pineapple
Answer:
(1) chloroplast in leaves

Question 10.
Ethylene promotes …………..
(1) senescence and abscission of flowers
(2) senescence but not abscission of flowers
(3) abscission of flowers but not senescence
(4) neither senescence nor abscission of flowers
Answer:
(1) senescence and abscission of flowers

II. Plant Growth and Development Fill in the Blanks (1 Mark)

Question 1.
Auxin was isolated by F.W.Went from tips of coleoptiles of ………… seedlings.
Answer: :
Oats

Question 2.
The ‘Bakanae’ disease of rice seedlings was caused by a fungal pathogen …………
Answer:
Gibberella fujikuroi

Question 3.
Skoog and Miller crystallized the cytokinesis promoting active substance that they termed as …………
Answer:
Kinetin

Question 4.
Inhibitor-B and Dormin were proved to be chemically identical and was named …………
Answer:
ABA/Abscisic acid

Question 5.
NAA and 2,4-D are ………… auxins.
Answer:
Synthetic

Question 6.
2,4-D is widely used to kill ………… weeds.
Answer:
Dicot

Question 7.
………… PGR causes elongation of apple fruits and improves its shape.
Answer:
Gibberellins

Question 8.
Natural cytokinin zeatin was extracted from ………… and Coconut milk.
Answer:
Corn kernels

Question 9.
The rise in rate of respiration during ripening of fruits is called as …………
Answer:
Respiratory climactic

Question 10.
………… Plant growth regulator is called stress hormone.
Answer:
ABA/Abscisic acid

III. Plant Growth and Development One Word Answer Questions (1 Mark)

Question 1.
In which phase of growth is most rapid ?
Answer:
Log phase

Question 2.
Name the hormone that induce rooting in stem cutting.
Answer:
Auxins

Question 3.
Apical dominance is induced by which hormone?
Answer:
Auxins

Question 4.
Name the auxin that kills dicotyledonous weeds.
Answer:
2,4 D

Question 5.
Which hormone is useful for ripening of fruits ?
Answer:
Ethylene

Question 6.
Name the phytohormone useful for closure of stomata.
Answer:
ABA

Question 7.
Name the fungus responsible for discovery of gibberellins.
Answer:
Gibberella fujikuroi

Question 8.
Which phytohormone induces bolting in rosette plants ?
Answer:
Gibberellins

Question 9.
Name the phytohormone which is isolated from corn kernels and coconut milk.
Answer:
Zeatin

Question 10.
Which phytohormone promotes female flowers in cucumbers?
Answer:
Ethylene

IV. Plant Growth and Development Very Short Answer Questions (2 Marks)

Question 1.
Define plasticity ? Give an example.
Answer:
Plasticity is the ability of plants to follow different developmental pathways in response to environmental conditions or life stages.
Example : Heterophylly in buttercup, where leaf forms differ in air and water habitats. Cotton, Coriander, and Larkspur.

Question 2.
What is the disease that formed the basis of the identification of gibberellins in plants? Name the causative fungus of this disease.
Answer:
The disease that formed is Bakanae or “foolish seedling” disease of rice seedlings. It is caused by Fungal pathogen Gibberella fujikuroi.

Question 3.
What is apical dominance? Name the growth hormone that causes it.
Answer:

• Apical dominance is the inhibition of lateral (axillary) bud growth by the apical bud.
• The growth hormone that caused is Auxin.

Question 4.
What is meant by bolting ? Which hormone causes bolting ?
Answer:

• Bolting is the elongation of the internode just before flowering.
• The Hormone that causes bloting is Gibberellins.

Question 5.
Define respiratory climactic? Name the PGR associated with it.
Answer:

• Respiratory climactic is the sudden rise in respiration rate during fruit ripening.
• PGR that associated with it is Ethylene.

Question 6.
What is ethephon? Write its role in agricultural practices.
Answer:

• The most widely used compound as a source of ethylene is ethephon.
• Ethephon is a chemical that releases ethylene slowly in plants.
• It hastens fruit ripening in tomatoes and apples, induces flowering, promotes abscission, and increases female flowers in cucumbers, thereby increasing the yield.

Question 7.
Why is abscisic acid also known as stress hormone ?
Answer:

• Abscisic acid is also known as stress hormone.
• ABA increases a plant’s tolerance to stress and induces stomatal closure during water shortage.

Question 8.
Define growth and development.
Answer:
Growth: It is an irreversible increase in size, such as length or weight.
Development: It includes all changes during the life cycle of a plant-from germination to senescence – including growth and differentiation.

Question 9.
Name the phases observed in sigmoid growth curve.
Answer:

• Lag phase
• Log (exponential) phase
• Stationary phase.

Question 10.
What are the very essential conditions required for growth ?
Answer:
The very essential conditions required for growth is water, oxygen, nutrients, optimum temperature, and environmental signals like light and gravity.

V. Plant Growth and Development Short Answer Questions (4 Marks)

Question 1.
Write a note on agricultural and horticultural applications of auxins.
Answer:
Auxins such as IAA (Indole-3-acetic acid), IBA (Indole butyric acid), NAA (Naphthalene acetic acid), and 2,4-D (2,4-dichlorophenoxyacetic acid) are widely used in agriculture and horticulture for several purposes :

• Auxins help initiate rooting in stem cuttings, making them essential in vegetative propagation.
• Auxins are used to promote flowering in pineapples.
• Auxins prevent premature dropping of fruits and leaves.
• Synthetic auxins like 2,4-D selectively kill dicot weeds without affecting monocot plants, making them useful in maintaining weed-free lawns and fields.
• Auxins can induce seedless fruit development, E.g. : in tomatoes.
• Auxins also control xylem differentiation and promote cell division.
• Auxins used in pruning practices like decapitation to encourage bushier growth in tea plantations and hedges by removing the apical bud.

Question 2.
Write the physiological responses of the gibberellins in plants.
Answer:
Gibberellins (GAs), such as GA₃, exhibit several physiological effects in plants :

• Stem elongation: They promote elongation of the plant axis, which is used to increase the length of grape stalks and sugarcane stems, thereby improving yield.
• Fruit development : Gibberellins cause fruits like apple to elongate and improve in shape.
• Delay in senescence: This allows fruits to remain longer on the tree, extending the market period.
• Seed germination and malting: GA₃ is used to speed up the malting process in brewing by promoting enzyme production.
• Early seed production: Spraying juvenile conifers with gibberellins accelerates their maturity and seed production.
• Bolting: In plants with rosette habits (like beet and cabbage), gibberellins promote internode elongation before flowering.
• Breaking dormancy : They assist in breaking seed dormancy and initiating germination.

Question 3.
Write any four physiological effects of cytokinins in plants.
Answer:

• Cytokinins induce cell division.
• Cytokinins help to produce new leaves, chloroplasts in leaves.
• Cytokinins help in lateral shoot growth and adventitious shoot formation.
• Cytokinins help to overcome apical dominance.
• They promote nutrient mobilization which helps in the delay of leaf senescence.
• Cytokinins help in the opening of stomata by increasing the concentration of K⁺ ions in guard cells.

Question 4.
What are the physiological processes that are regulated by ethylene in plants ?
Answer:

• Fruit Ripening: Ethylene promotes ripening in fruits and enhances the respiration rate during this process, known as the respiratory climactic.
• Senescence and Abscission : It induces senescence (aging) and abscission (shedding) of leaves, flowers, and fruits.
• Seed and Bud Dormancy Breaking: Ethylene breaks seed and bud dormancy and promotes germination (E.g. : in peanuts and sprouting in potato tubers).
• Stem Elongation and Hook Formation: It stimulates rapid internode and petiole elongation in deepwater rice and supports apical hook formation in dicot seedlings.
• Root Growth and Root Hair Formation : Ethylene promotes the growth of roots and formation of root hairs, improving water and nutrient absorption.
• Flowering Induction: It induces flowering in certain plants like mango and is used to synchronize fruit-set in pineapples.
• Agricultural Uses via Ethephon: Ethylene released from ethephon hastens ripening (E.g. : in tomatoes and apples), promotes abscission in crops like cotton and walnut, and increases female flowers in cucumbers.

VI. Plant Growth and Development Long Type Questions (8 Marks)

Question 1.
Define growth, differentiation, development, dedifferentiation, redifferentiation, determinate growth, meristem and growth rate.
Answer:
1. Growth: Growth is an irreversible, permanent increase in size of an organ or its parts or even of a single cell. It involves increase in length, area, volume, or cell number and is usually accompanied by metabolic activity.

2. Differentiation : It is the process by which cells formed from apical meristems or cambium undergo structural changes and mature to perform specific functions, like tracheary elements developing thick walls and losing protoplasm.

3. Development: Development is the sum total of growth and differentiation. It includes all the changes an organism undergoes in its life cycle from germination to senescence. It is regulated by both internal and external factors.

4. Dedifferentiation: This refers to the process by which mature, differentiated cells regain the ability to divide under certain conditions, forming new meristematic tissues. For example, parenchyma cells forming interfascicular or cork cambium.

5. Redifferentiation : Cells produced from dedifferentiated tissues lose the power of division again and mature into specialized cells. This process is called redifferentiation, such as formation of protective tissues from cork cambium cells.

6. Determinate Growth : Determinate growth refers to growth that stops after reaching a particular size or stage. Examples include leaves, flowers, and fruits which have limited growth periods.

7. Meristem: Meristems are groups of undifferentiated, actively dividing cells in specific regions like root and shoot tips. They are responsible for primary and secondary plant growth.

8. Growth Rate: Growth rate is the amount of growth per unit time. It may be arithmetic (linear increase) or geometric (exponential increase), and is measured as either absolute or relative growth rate.

Question 2.
Describe briefly
a) Arithmetic growth
b) Geometric growth
c) Sigmoid growth curve
d) Absolute and relative growth rates
Answer:
a) Arithmetic Growth : In arithmetic growth, following mitotic division, only one daughter cell continues to divide, while the other differentiates and matures. It results in a linear increase in growth over time.
Rate of Growth: The growth rate is constant, meaning the increase in size or number is the same over equal time intervals.
Ex : The elongation of roots at a constant rate is an example of arithmetic growth.
Graph: A graph of length against time in arithmetic growth results in a straight line (linear curve).

b) Geometric Growth: In geometric growth, both daughter cells formed after mitotic division retain the capacity to divide. This leads to exponential growth, especially during the log phase. It starts with a lag phase (slow growth), followed by a log phase (rapid growth), and ends with a stationary phase when resources become limited.
Rate of Growth: The initial growth is slow (lag phase), followed by a period of rapid increase (log/exponential phase), and then a slowing phase.
Ex : The growth of all cells, tissues, and organs generally follows a geometric pattern.
Graph : A graph of size against time in geometric growth shows a S-shaped curve (sigmoid curve).

c) Sigmoid Growth Curve : When geometric growth is plotted against time, a characteristic S-shaped or sigmoid curve is observed.

1. Phases of sigmoid curve :

• Lag phase – initial slow growth
• Log (exponential) phase – rapid growth
• Stationary phase – growth slows and stabilizes

2. The sigmoid curve is typical for most cells, tissues, organs, and wholeplants growing under natural conditions.

d) Absolute and Relative Growth Rates:

• Absolute Growth Rate: It is the total growth per unit time.
  Example: Increase in length or weight of an organ in a given time
• Relative Growth Rate: It is the growth per unit time per unit initial parameter, such as initial size. It shows the efficiency of growth and allows comparison between organs of different sizes.
  Example: A small leaf showing higher percentage increase in area compared to a larger one, even if the absolute growth is the same.

Plant Growth and Development Class 11 Extra Questions and Answers

I. Multiple Choice Questions (1 Mark)

Question 1.
Rose plants which are propagated through stem cuttings are often sprayed with synthetic auxin solutions because
(1) auxin promotes shoot elongation
(2) auxin promotes rooting in shoots
(3) auxin promotes cell expansion
(4) auxin promotes cell division
Answer:
(2) auxin promotes rooting in shoots

Question 2.
A leaf having a surface area of 25cm² grows to 30cm² in one hour. Calculate its relative growth rate.
(1) 25 %
(2) 20 %
(3) 100 %
(4) 0 %
Answer:
(2) 20 %

Question 3.
Discovery of how many out of 5 major PGRs was accidental ?
(1) 2
(2) 1
(3) 3
(4) 5
Answer:
(4) 5

Question 4.
A gaseous PGR is………….
(1) ABA
(2) Ethylene
(3) GA₃
(4) IAA
Answer:
(2) Ethylene

Question 5.
An example of adenine derivative PGR
(1) IAA
(2) Kinetin
(3) ABA
(4) Gibberellic acid
Answer:
(2) Kinetin

Question 6.
Plant grows throughout the life due to …………………
(1) Meristematic tissue
(2) Parenchyma tissue
(3) Epidermal tissue
(4) Special tissue
Answer:
(1) Meristematic tissue

Question 7.
Growth can be measured by measuring increase in …………………
(1) Amount of protoplasm
(2) Dry weight
(3) Cell number
(4) Both 2 and 3
Answer:
(4) Both 2 and 3

Question 8.
Increased vacuolation is a characteristics of…………………
(1) Meristematic phase
(2) Maturation phase
(3) Elongation phase
(4) Root cap zone
Answer:
(3) Elongation phase

Question 9.
The three phases of sigmoid growth occur in order are…………………
(1) Log, lag, stationary
(2) Log, stationary, lag
(3) Lag, log, stationary
(4) Lag, stationary, log
Answer:
(3) Lag, log, stationary

Question 10.
Plasticity can be seen in…………………
(1) Cotton
(2) Coriander
(3) Buttercup
(4) All of these
Answer:
(4) All of these

II. Fill in the Blanks (1 Mark)

Question 1.
The first cytokinin was discovered by …………
Answer:
Miller

Question 2.
The habits of Cabbage plant can be changed drastically by the application of …………
Answer:
GA₃

Question 3.
During plant growth, ………… phase precedes flowering.
Answer:
Vegetative

Question 4.
Development is the sum total of two processes, named …………
Answer:
Growth and differentiation

Question 5.
Growth is accompanied by ………… processes that occur at the expense of …………
Answer:
Metabolic, energy

Question 6.
Name the type of growth where in new cells are always being added to the plant body by the activity of meristem ………… Answer:
Open form of growth

Question 7.
Auxin was first isolated from …………
Answer:
Human urine

Question 8.
2,4-D is used to …………
Answer:
Kill dicotyledonous weeds

Question 9.
Ethylene promotes ………… in cucumber.
Answer:
Female flowers

Question 10.
The growth regulator that retards ageing of plant organ is …………
Answer:
Cytokinin

Question 11.
A tree showing seasonal activities and cells in culture exhibit ………… (sigmoid/linear) growth curve.
Answer:
Sigmoid

Question 12.
A tumour is an example of …………
Answer:
defifferentiation

Question 13.
In case of geometric growth rate, ………… (no cell/both the daughter cells) divide following the mitotic cell division.
Answer:
Both the daughter cells)

III. One Word Answer Questions (1 Mark)

Question 1.
Name the hormone which initiates rooting in stem cutting, flowering in pineapples and promotes abscission of older leaves and fruits.
Answer:
Auxins

Question 2.
Name the phenomenon in which the growing apical bud inhibits the growth of lateral or axillary buds.
Answer:
Apical dominance

Question 3.
Name any two sources of zeatin.
Answer:
Coconut milk and Corn-Kernels

Question 4.
Name the hormone which promotes horizontal growth of seedling, fruit ripening and senescence and abscission of leaves and flowers.
Answer:
Ethylene

Question 5.
Mention the function of ethylene in pineapples.
Answer:
Initiate flowering and synchronizing fruit set.

Question 6.
Name the most widely used compound as source of ethylene in agriculture.
Answer:
Ethephon

Question 7.
Name the hormone which acts as antagonistically to ABA.
Answer:
Gibberellic acid

Question 8.
Name the three phases of the period of growth.
Answer:
Meristematic phase, elongation phase and maturation phase

Question 9.
Name the device that is used to growth rate.
Answer:
Auxanometer

Question 10.
Name any three essential elements for growth.
Answer:
Water, Oxygen, Macro and Micronutrient

Question 11.
The ability of plants to follow different pathways in response to environment or phases of life to form different structures is called heterozygosity.
(Rewrite the statement after correcting the underlined word)
Answer:
Plasticity