Tag: sense organs in animals

Questions Related to sense organs in animals

Choose the correct answer from the alternatives given.
Which of the following statements about plant hormones is not true?

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

  1. Each naturally occurring hormone has a specific chemical structure

  2. Hormones are among the principal internal regulators of plant growth

  3. Responses to plant hormones may be observed in nearly any part of a plant

  4. All known growth regulators of plant activities are chemicals produced naturally in plants

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Correct Option: D
Explanation:

Cytokinins have specific effects on cytokinesis and were discovered as kinetin (a modified form of adenine, a purine) from the autoclaved herring sperm DNA. Kinetin does not occur naturally in plants.

So, the correct option is 'All known growth regulators of plant activities are chemicals produced naturally in plants'.

Choose the correct answer from the alternatives given.
Plant hormones

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

  1. interact with one another

  2. are influenced by environmental cues

  3. are active in plant embryos within seeds

  4. all of the above

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Correct Option: D
Explanation:

Plant hormones can work in combination and are dependent on the environmental cues or signals to act. They are also active in plant embryos within the seed such as Gibberellic acid.

So, the correct option is 'all of the above'.

Choose the correct answer from the alternatives given.
The mitotically active and hormone producing cells are:

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

  1. xylem

  2. meristem

  3. phloem

  4. cortex

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Correct Option: B
Explanation:

Meristem is the actively dividing cells at the root and shoots apices that are mitotically active.

So, the correct option is 'meristem'.

Choose the correct answer from the alternatives given.
The plant hormone that causes cell elongation is:

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

  1. citric acid

  2. indole 3-acetic acid

  3. ethylene

  4. abscisic acid

Show answer
Correct Option: B
Explanation:

Plant cells elongate irreversibly only when load-bearing bonds in the walls are cleaved. Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds. This process may be coupled with the intercalation of new cell wall polymers.

So, the correct option is 'indole 3-acetic acid'.

Find the odd man out:

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

  1. Auxin

  2. Abscisic acid

  3. Thyroxine

  4. Gibberellin

Show answer
Correct Option: C
Explanation:

  • Auxin is a plant hormone that is produced in the tip of the stem that works in elongation.
  •  Auxin helps the plant to move to the darker side, the cell grows larger than corresponding cells present on the lighter side of the plant.
So, the correct option is 'Auxin'.

Which of the following hormones contains nitrogen?

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

  1. Auxin

  2. Cytokinin

  3. Gibberelins

  4. Both 1 and 2

Show answer
Correct Option: D
Explanation:

Auxin and cytokinin both contain nitrogen in their structure. 

So the correct option is "Both 1 & 2". 

Two plant hormones which regulate growth of plant are?

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

  1. Cytokinin and Auxin

  2. Abscisic acid and Auxin

  3. Auxin and Gibberellin

  4. All of these

Show answer
Correct Option: A

Match the Column-I and Column-II.

Column-I Column-II
(i) Auxin (A) Adenine derivatives
(ii) Gibberellin (B) Carotenoid derivatives
(iii) Cytokinin (C) Terpins
(iv) ABA (D) Indole compounds
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

  1. i-B, ii-A, iii-D, iv-C

  2. i-D, ii-B, iii-A, iv-C

  3. i-B, ii-A, iii-C, iv-D

  4. i-D, ii-C, iii-A, iv-B

Show answer
Correct Option: D

A high concentration of synthetic auxin is generally used for

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

  1. Weed control

  2. Preventing the growth of the lateral buds

  3. Enhancing root initiation

  4. Controlling of cell enlargement

Show answer
Correct Option: A
Explanation:

In the course of research on auxin biology, many compounds with noticeable auxin activity were synthesized. Many of them had been found to have the economical potential for man-controlled growth and development of plants in agronomy. 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. However, synthetic auxins, especially 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA), are also commonly applied to stimulate root growth when taking cuttings of plants or for different agricultural purposes such as the prevention of fruit drop in orchards. Used in high doses, auxin stimulates the production of ethylene. Excess ethylene (also native plant hormone) can inhibit elongation growth, cause leaves to fall (abscission), and even kill the plant. 

Therefore, the correct answer is option A.

During adverse environmental conditions, plants develop a stress hormone, which is

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

  1. Abscisic acid

  2. Ethylene

  3. Benzyl amino purine

  4. Dichlorophenoxy acetic acid

Show answer
Correct Option: A
Explanation:
Abscisic acid or ABA plays a regulatory role in many physiological processes in plants. Different stress conditions such as water, cold, light, and temperature result in increased amounts of ABA. The action of ABA involves modification of gene expression and analysis of responsive promoters revealed several potential cis- and trans- acting regulatory elements. Stress may induce common responses such as enhancement of plant hormones. For instance, wounding can induce the production of increased ethylene, auxin, and abscisic acid (ABA). Since, many kinds of stresses including water, salt, and cold temperatures, induce ABA synthesis, ABA may be considered a plant stress hormone. It regulates several important aspects of plant growth and development. Recent studies have demonstrated a pivotal role for ABA in modulation at the gene level of adaptative responses for plants in adverse environmental conditions.