Biology

Plant Growth and Hormones

727 Questions

Plant growth and hormones is a vital topic in biology that covers the physiological effects of different plant regulators like auxins, gibberellins, and cytokinins. These concepts are frequently tested in various general science sections of competitive exams. Practicing these questions helps clarify complex mechanisms like vernalisation, senescence, and tropism for test takers.

Abscisic acid effectsCytokinin functionsAuxins and tropismPlant tissue cultureSenescence in plantsNatural plant hormones

Plant Growth and Hormones Questions

Multiple choice biology concept of life living organism living vs nonliving living vs non living

Plant response to environment is mainly through

  1. Induction of dormancy

  2. Abscission of parts

  3. Synthesis of pigments

  4. Growth
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Plants respond to their environment to ensure their survival. Plants response to environment is mainly through growth, either towards or away from stimuli. This type of response is called as tropism. It is brought about by hormones, which control plant growth and development.

Thus, the correct answer is option D.

Multiple choice mitosis structure of chromosome, cell cycle and cell division cell division biology cell division in embryo development division for growth and reproduction

Storage sprouting of potato can be prevented by 

  1. IAA

  2. Maleic hydrazide

  3. Cytokinins

  4. Gibberellins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Maleic hydrazide : It is a growth retardant which checks cell division. So during seed storage this is applied for checking sprouting of potato tubers so that the importance of potato may not be lowered down.

Multiple choice botany mineral nutrition in plants deficiency diseases and symptoms deficiency symptoms macronutrients and micronutrients

Necrosis refers to 

  1. Inhibition of cell division

  2. Delay in flowering

  3. Death of tissues

  4. Falling of leaves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a living organism's cells or tissues die or degenerate, the condition is called necrosis. In a plant, necrosis causes leaves, stems and other parts to darken and wilt. Necrosis weakens the plant and makes it more susceptible to other diseases and pests. 

Thus, the correct answer is 'Death of tissues.'

Multiple choice botany cell theory, cell specialization, and cell replacement number and shape of cells unicellular and multicellular organisms diversity and classification in animals

Read the given statements and select the correct option.


(i) One maize root cell can give rise to more than 17,500 cells.
(ii) A cell in watermelon can increase in size upto 3,50,000 times.
(iii) The growth of pollen tube is measured in terms of length.
(iv) The growth of the leaf is measured in term of surface area.

  1. Statements (i) and (ii) are correct.

  2. Statements (iii) and (iv) are correct.

  3. Statements (i) and (iii) are correct.

  4. Statements (i), (ii), (iii) and (iv) are correct.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The root cells may give rise to more than 17,500 cells, the cells of the root undergo mitotic division in an arithmatic manner, where some of the dividing cells undergo differentiation while others continue to divide.

A water melon pulp contains about 90% of water, so the enormous increase in size of the cell is due to endosmosis.
The growth of the pollen tube is measures in $\mu$ meters
A leaf visually is a two dimensional structure hence it is measured in terms of surface area.
So, the correct answer is 'Statements (i), (ii), (iii) and (iv) are correct.'

Multiple choice types of endosperms plant kingdom biology

Which one of the following phytochromones is associated with seed maturation?

  1. ABA

  2. Kinetin

  3. Ethylene

  4. IAA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Abscisic acid (ABA) is the primary plant hormone associated with seed maturation, dormancy induction, and stress response. It prevents premature germination.

Multiple choice biology water absorption and ascent of sap in plants transport of water across plants habit of plants plant classifications

Assertion : Auxins promote apical dominance by suppressing the activity pf lateral buds.

Reason : In moriculture, periodic pruning of shoot tips is done to make mulberry plants bushy.

  1. If both the assertion and reason are true and the reason is a correct explanation of the assertion

  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion

  3. If the assertion is true but the reaon is false

  4. If both the assertion and reason are false

  5. If the assertion is false but reason is true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Auxin is produced by shoot tip and acts as a growth promoter for apical bud and inhibit the growth of lateral buds. When a terminal bud is removed, the nearest axillary buds begin to grow and the plant branches rapidly. In case of mulberry plants, pruning is done to remove apical dominance and causes more branching of the main body of the plant.

Multiple choice biology photosynthesis and respiration experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

A green plant bends towards the source of light when exposed to the light on only one side, it bends towards the source of light as it grows. Which of the following is the best explanation of the phenomenon 

  1. The apices of their stems are attracted by light

  2. They need light for photosynthesis

  3. Some auxins accumulates on the shaded side to induce greater cell elongation on that side

  4. Light stimulates the cells on the illuminated side to increase in length
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Accumulation of auxin as the apex of the plant, which is responsible for the phototropism movement so that plant cells are elongated.

So the correct option is C.

Multiple choice chemistry water in our life how can we conserve water? droughts, floods and water conservation conservation of water and its importance and methods

Which hormone level increases during water scarcity condition?

  1. Auxin

  2. Cytokinine

  3. Abscisic acid

  4. Ethylene
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Abscisic acid (ABA) is known as a stress hormone in plants. Its levels increase significantly during water scarcity to induce stomatal closure, which helps the plant conserve water.

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

In organs of plants there is a variation in rate of growth. It is first slow, then accelerated upto maximum and slows down to stand still. The period of vigorous growth is known as

  1. Lag phase

  2. Period of growth

  3. Grand period of growth

  4. Log phase
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
In organs of plants, there is a variation in rate of growth. Growth is divided into four phases, namely lag phase, log phase, stationary phase and death phase. Lag phase is slow. In this, 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. It is the period of vigorous 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 D.
Multiple choice biology plant growth growth rates and conditions for growth population ecology growth and development

State whether the following statements are true or false.
Ethylene stimulates leaf release, while auxin keeps leaves from falling.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ethylene is a gaseous hormone which stimulates the transverse growth but inhibits the longitudinal growth. Auxin delays the abscission of young leaves and provides nutrition to it so that they do not die down while ethylene increases the senescence of leaves and flowers and produces more gas which leads to loss of leaves.

So, the correct statement is 'True'.

Multiple choice evs seed becomes plant germination of seed seed germination journey of seed

All of the following statements about the role played by water in the growth of plants are true, except

  1. It is a solvent in which several substances are dissolved.

  2. It participates as a reagent in many reactions.

  3. It helps in the germination of seeds but does not provide turgidity to growing cells.

  4. It serves as the medium for transport of inorganic salts.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Water, being the universal solvent helps in germination of seeds and provide turgidity to growing cells. Turgidity or turgidness, is caused by the osmotic flow of water from an area of low solute concentration outside of the cell into the cell's vacuole, which has a higher solute concentration. Healthy plant cells are turgid and plants rely on turgidity to maintain rigidity. 
Refer the picture for turgidity in plant cells.
Role of water in plant growth:
  • Primary component of photosynthesis and transpiration.
  • Turgor pressure (pressure to inflate cells and hold plant erect).
  • Solvent to move minerals from the soil up to the plant.
  • Solvent to move products of photosynthesis throughout the plant, including down to the root system.
  • Regulation of stomatal opening and closure, thus regulating transpiration and photosynthesis.
  • Source of pressure to move roots through the soil.
  • Medium for biochemical reactions.
Hence, the correct answer is option C.
Multiple choice evs seed becomes plant germination of seed seed germination journey of seed

Seasonal growth cycle of plants can be influenced by

  1. Temperature

  2. Amount of water

  3. Amount of daylight

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The growth cycle in plants shows seasonal variations. Plants are of various types such as annuals, biennials and perennials. Also, the vegetative and reproductive growth of plants depends upon factors such as temperature, water availability and the amount of day light they are exposed to. Accordingly, there are short day, long day and day neutral plants.
So, the correct answer is, 'All of the above'.
Multiple choice evs seed becomes plant germination of seed seed germination journey of seed

Choose the correct answer from the alternatives given.
The ripening of fruits can be accelerated by:

  1. artificially adding ethylene gas to the atmosphere surrounding them

  2. warming the surroundings artificially

  3. keeping the fruits in a refrigerator

  4. reducing water supply to the plant when the fruits are maturing
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. 

So, the correct option is 'artificially adding ethylene gas to the atmosphere surrounding them'.

Multiple choice biology food and human health balanced diet and malnutrition balanced and unbalanced food digestive disorders diseases caused by changes in lifestyle diseases and toxic substance health and its maintenance

Richmond-Lang effect is 

  1. The effect of kinetins in delaying senescence

  2. The effect of colines on root and shoot formation

  3. The effect of traumatic acid in wound formation

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cytokinins delay the senescence of leaves and other organs by controlling protein synthesis and mobilization. Reported by "Richmond and Lang" in 1957 working on "Xanthium leaves".