Tag: growth and development

Questions Related to growth and development

Exponential growth is shown during

biology plant growth growth rates and conditions for growth population ecology growth and development

  1. Lag phase

  2. Log phase

  3. Maturation phase

  4. Senescence phase

Show answer
Correct Option: B
Explanation:
Bacterial growth is divided into four phases, namely lag phase, log phase, stationary phase and death phase. In lag phase, there is very little or no bacterial growth. In this phase, bacteria are adjusting to environment and synthesizing biochemicals and nutrients. In log phase, the number of bacterial cells doubles at an exponential rate. This phase shows maximum or exponential growth. In stationary phase, the rate of cell death is equal to the rate of cell division. In death phase, there is decrease in the bacterial population due to lack of nutrients and high toxin concentration.
Thus, the correct answer is option B.

Choose the correct answer from the alternatives given.
The auxanometer is used for measuring the:

biology growth and development growth rates and conditions for growth population ecology plant growth

  1. growth of a fruit

  2. growth of a cell

  3. width of the stem

  4. length of the stem

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Correct Option: D

Apical dominance in higher plants is due to 

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Enzyme activity

  2. Photoperiodism

  3. Carbohydrate-nitrogen ratio

  4. Balance between auxin and cytokinins

Show answer
Correct Option: D
Explanation:

Apical dominance is a phenomenon in which central stem is dominant and lateral stems are suppressed. It is due to plant hormones produced in the tip of the shoot. Auxin hormone is responsible for apical dominance and cytokinin hormone is responsible for breaking the apical dominance. Hence, apical dominance depends on the auxin to cytokinin balance. 

Thus, the correct answer is option D.

Study the following statements and select the correct ones.

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Auxin is transported from base to tip in large quantities.

  2. Cells on the dark side expand farther than those on the light side.

  3. Apical dominance can be removed the decapitation

  4. Tropic movements in plants are under the control of gibberellins

Show answer
Correct Option: C
Explanation:

Decapitation involves cutting of apical bud in plants. When the apical bud is removed, the source of auxin is removed. Auxin causes apical dominance. Since the auxin concentration is much lower, the lateral buds can now grow. In fact, their growth will be stimulated by a relatively small drop in auxin concentration. Thus, decapitating a shoot will cause it to branch.

So, the correct option is 'Apical dominance can be removed the decapitation'.

Which of the following characterstic is not represented in 'Inheritance of seed characters' like shape and starch grain size in garden pea ?

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Dominance

  2. Incomplete dominance

  3. Polygenic inheritance

  4. Pleiotropy

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Correct Option: A

Select the correct one.

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Beer produced by distillation of fermented broth

  2. Bottled juices are cleared by protease and pectinase

  3. Methanogens digest cellulose aerobically

  4. Streptokinase is used to lower the blood cholesterol

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Correct Option: B

Which growth hormone is responsible for apical dominance?

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. Auxin

  2. Cytokinin

  3. Gibberellin

  4. Ethylene

Show answer
Correct Option: A
Explanation:

Auxin exerts profound effects on plants. For example, some plants tend to branch out very little when they grow. Growth in these plants occurs almost exclusively from the apical meristem rather than from axillary buds, which do not develop as long as the terminal bud is present. Such plants are said to exhibit apical dominance, the inhibition of axillary bud growth by the apical meristem. In plants with strong apical dominance, auxin produced in the apical meristem inhibits axillary buds near the apical meristem from developing into actively growing shoots. When the apical meristem is pinched off, the auxin source is removed and axillary buds grow to form branches. Apical dominance is often quickly re-established, however, as one branch begins to inhibit the growth of others.

Thus, the correct answer is option A.

How does pruning help in making the hedge dense?

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. It releases wound hormones.

  2. It induces the differentiation of new shoots from the rootstock.

  3. It frees auxillary buds from apical dominance.

  4. The apical shoot grows faster after pruning.

Show answer
Correct Option: C
Explanation:

Auxin is the phytohormone which is responsible for promoting apical dominance in plants. Auxin is usually seen at the growing tips of plants. Thus the auxin present at the tip of plants will be channelized sidewards, lateral meristem; so that the plants will not grow tall but instead becomes bushy in nature.

Which of the following is responsible for apical dominance ?

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. GA$ _3$

  2. IAA

  3. ABA

  4. Florigen

Show answer
Correct Option: B
Explanation:

Auxins promote elongation of stem and coleoptile. It promotes the growth by the elongation of cells in the apical meristem. Growth in the lateral bud is inhibited when the apical bud of a tall plant remains intact. However, the lateral bud grows rapidly on the removal of apical bud. Suppression of growth in the lateral bud by apical bud due to auxin produced by apical bud is termed as apical dominance. IAA is an example of auxin. 

Thus, the correct answer is option B. 

Which hormone is responsible for apical growth?

apical dominance auxins and gibberellins growth and development plant growth and development biology

  1. IAA

  2. ABA

  3. GA

  4. All of the above

Show answer
Correct Option: A
Explanation:

Auxins (like IAA) and gibberellins (GA) are growth promoting phytohormones. IAA promotes apical growth whereas GA causes internodal elongation. Promotion of apical growth by auxins and suppression of axillary growth is also called as apical dominance.

Thus, the correct answer is option A.