Biology

Plant Growth and Hormones

695 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 life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Chemicals having profound effect on growth and development are

  1. Enzymes

  2. Phytohormones

  3. Catalytic agents

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

Phytohormones are also called as plant hormones. These are chemicals which play important role in growth and development of plants. These are involved in various physiological processes of plants like growth, flowering, fruiting, shoot and root development, etc. Phytohormones liks auxin, cytokinin act as growth promoter whereas hormones like abscisic acid, ethylene act as growth inhibitor. 

Thus, the correct answer is option B.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Through their effect on phytohormones, temperature and light control

  1. Stomatal closure

  2. Apical dominance

  3. Flowering

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

Phytohormone is the plant hormone that is involved in various processes of plants. Hormones like gibberellin induce flowering and abscisic acid inhibits flowering in plants. In plants, flowering is controlled by light and dark periods (photoperiod) and temperature in specific environments. Plant generally requires either long day or cold condition for flowering.

Thus, the correct answer is option C.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Phytohormone is a naturally produced organic substance in ________________.

  1. Higher plants which controls growth and development in general

  2. Plants to control growth and physiological functions at the site of its production

  3. Higher plants controlling growth and development at a site for removed from the site of its production and is effectively only when present in large quantities

  4. Higher plant controlling physiological and growth functions at a site quite removed form the site of its production and is effective when present when in minute quantities
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

High concentration of hormone will

  1. Kill the plant

  2. Cause chlorosis in leaves

  3. Cause stunting in plants

  4. Show no effect on the plant
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When concentration of hormones in the plant body increases, growth of the plants decreases.

So, the correct option is cause stunting in plants’.

Multiple choice biology life processes: control and coordination control and coordination in plants growth in plants chemical coordination in plants animal senses sense organs in animals sense organs in humans

Identify the physiological process induced by two phytohormones having a common precursor which is formed due to catalytic activity of pyruvic dehydrogenase complex
(a) More female flowers in Cucumber
(b) $\alpha$-amylase production in Barley grains
(c) Acceleration of fruit ripening in Tomato
(d) Delay in sprouting of Potato tubers.

  1. a, b

  2. a, c

  3. c, d

  4. b, d
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ethylene is a plant hormone. It accelerates fruit ripening in tomato. Maleic hydrazide is a type of auxin, plant hormone. It delays sprouting of potato tubers. Both these hormones have common precursor that is formed due to the catalytic activity of pyruvic dehydrogenase complex.

Thus, the correct answer is option C.

Multiple choice biology chemical coordination and integration hormones coordination in human beings- chemical control endocrine system in humans

Which hormone inhibit morphogenesis?

  1. ABA

  2. 2, 4-D

  3. Jasmonic acid

  4. IBA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The plant hormone abscisic acid (ABA) has been shown to promote abscission and dormancy, to inhibit cell elongation and to be involved in several hormones mediated plant responses
  • ABA inhibits seed germination.It also inhibits morphogenesis(It is the biological process that causes an organism to develop its shape).
  • So, the correct answer is 'ABA'.
Multiple choice botany reproduction in angiospermic plants artificial vegetative propagation common modes of vegetative propagation vegetative propagation asexual modes of reproduction

Which of the following defines phytotron?

  1. Fish culture facility

  2. Plant hormone

  3. Secondary metabolite

  4. Controlled plant culture facility
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A phytotron is an enclosed research greenhouse used for studying interactions between plants and the environment. It was a product of the disciplines of plant physiology and botany. The first phytotron was built under the direction of Frits Warmolt Went at the California institute of Technology in 1949. It was funded by the Harry B. Earhart Foundation and was officially known as the Earhart plant research Laboratory.

Multiple choice botany reproduction in angiospermic plants artificial vegetative propagation common modes of vegetative propagation vegetative propagation asexual modes of reproduction

A plant hormone that induces morphogenesis in plant tissue culture is

  1. Abscisic acid

  2. Gibberellin

  3. Cytokinin

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

Cytokinin is a plant hormone which is involved in various physiological processes. It promotes growth of shoot buds. It also induces cell division and shoot and root morphogenesis. In plant tissue culture, it is applied externally to induce morphogenesis

Thus, the correct answer is option C.

Multiple choice botany tissue culture common modes of vegetative propagation plant breeding for food production plant tissue culture

Callus is

  1. Plant hormone

  2. Root formation in culture media

  3. Plant by-product

  4. Undifferentiated mass of tissue
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Callus is a growing mass of unorganized plant parenchyma cells. It is mainly  used in plant tissue culture. So basically in other words, callus is a undifferentiated mass of tissue. 

Multiple choice botany tissue culture common modes of vegetative propagation plant breeding for food production plant tissue culture

Which increase shoot growth in callus culture?

  1. Cytokinin

  2. Auxin

  3. Gibberellin

  4. ABA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The callus is an unspecialized, unorganized, growing and dividing the mass of cells.
  • It produced when explants are cultured on the appropriate solid medium, with both auxin and cytokinin in correct conditions.
  • In Callus culture, Auxins increase root growth and cytokinins increase shoot growth.
  • Hence Cytokinin increase shoot growth in callus culture.
  • So, the correct answer is 'Cytokinin'.
Multiple choice zoology soil pollution industrial chemicals and their harmful effects toxic wastes and their effects soil pollution-causes

Which of the following is involved in inhibition of growth of plants which is produced due to human activities?

  1. Auxins

  2. Phytotoxin

  3. Mycotoxins

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

Auxin is a plant hormone which causes the elongation of cells in shoots and is involved in regulating plant growth.
Phytotoxins refers to substances that are inhibitory to the growth of or poisonous to plants. Phytotoxic substances may result from human activity, as with herbicides, or they may be produced by plants, by microorganisms, or by naturally occurring chemical reactions.
Mycotoxins are toxic chemical products produced by fungi that readily colonize crops.
Antitoxins are antibodies that counteracts a toxin.
So, the correct answer is option B.

Multiple choice zoology soil pollution industrial chemicals and their harmful effects toxic wastes and their effects soil pollution-causes

Synthetic auxin; 2,4,5-T, is rich in which of the following toxic compound?

  1. Pyrethrin

  2. Dioxin

  3. Thurioside

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

Auxins are toxic to plants in large concentrations; they are most toxic to dicots and less so to monocots. Because of this property, synthetic auxin herbicides, including 2,4-D and 2,4,5-T, have been developed and used for weed control. Dioxins are environmental pollutants. They belong to the so-called dirty dozen - a group of dangerous chemicals known as persistent organic pollutants (POPs). Dioxins are of concern because of their highly toxic potential. Experiments have shown they affect a number of organs and systems.
Once dioxins enter the body, they last a long time because of their chemical stability and their ability to be absorbed by fat tissue, where they are then stored in the body. Their half-life in the body is estimated to be 7 to 11 years. In the environment, dioxins tend to accumulate in the food chain. The higher an animal is in the food chain, the higher the concentration of dioxins.
The chemical name for dioxin is: 2, 3, 7, 8 - tetrachlorodibenzo para dioxin (TCDD). The name "dioxins" is often used for the family of structurally and chemically related polychlorinated dibenzo para dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Dioxins are mainly by-products of industrial processes but can also result from natural processes, such as volcanic eruptions and forest fires. Dioxins are unwanted by products of a wide range of manufacturing processes including smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides.

Multiple choice evs identifying the plants absorption of water from the soil root system the root system

Plants sense gravity with the help of

  1. Phytochromes

  2. Statoliths

  3. Phytohormones

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

In the root cap there is a special subset of cells, called as statocytes. Inside the statocyst cells, some specialized amyloplasts are involved in the perception of gravity by the plant (gravitropism). Statoliths settle at the bottom part of their cells and allow plants to sense gravity. Statoliths are also found in the endodermal layer of the inflorescence stem. The redistribution of auxin causes the shoot to turn in a direction opposite that of the gravity stimuli.

So, the correct answer is 'Statoliths'.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Hormone involved in phototropism is ____________.

  1. IAA

  2. gibberellin

  3. kinetin

  4. 2, 4-D.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Phototropic curvature is the result of uneven distribution of auxin. Darwin and Darwin observed that the coleoptiles of canary grass responded w unilateral illumination by growing towards the light source (phototropism). After a series of experiments, It was concluded that the tip of coleoptile contains auxin that caused the bending of the entire coleoptile in relation to the direction of light.