PLANT PHYSIOLOGY (Part-II)

1. Which of the following types of trees are also known as 'Sunlight loving trees'? [S.S.C. Online C.P.O.S.I. (T-I) 2.07.2017 (Shift-I)]

(a) Xerophytes
(b) Heliophytes
(c) Saprophytes
(d) Halophytes

Correct Answer: (b) Heliophytes

Solution:Heliophytes -
Heliophytes are plants, including trees, that are adapted to thrive in full sunlight. The prefix "helio-" refers to the sun.

2. The solar tracking (moving in the Sun's direction) of the sunflower is called _____ . [S.S.C. Online CHSL (T-I) 16.10.2020 (Shift-I)]

(a) Thigmotropism
(b) Heliotropism
(c) Phototropism
(d) Hydrotropism

Correct Answer: (b) Heliotropism

Solution:The solar tracking (moving in the Sun’s direction) of the sunflower is called Heliotropism. In these plants, the flexible part of the stem just below the flower, in response to the pressure of the motor cells, turns the flower in the direction of the Sun.

3. Which one of the following events in a botanical garden is never directly influenced by light? [S.S.C. Online Graduate Level (T-I) 2.09.2016 (Shift-II)]

(a) Flowering
(b) Photosynthesis
(c) Transpiration
(d) Fertilization

Correct Answer: (d) Fertilization

Solution:Fertilization -
Fertilization, the fusion of male and female gametes to form a zygote, is an internal process within the flower and is not directly influenced by light. While light can affect flowering (and thus indirectly influence fertilization timing), the act of fertilization itself doesn't depend on light.

4. What are the five main categories of hormones in plants? [S.S.C. Online C.P.O. S.I. 7.06.2016 (Shift-I)]

(a) Auxins, gibberellins, cytokinins, abscisic acid, and ethylene
(b) Auxin, gibberellin, amino acid, abscisic acid, and insulin
(c) Cytokinins, insulin, eicosanoids, polypeptides, and amino acids
(d) Cytokinins, insulin, eicosanoids, abscisic and amino acids

Correct Answer: (a) Auxins, gibberellins, cytokinins, abscisic acid, and ethylene

Solution:The five main categories of hormones in plants are:

Auxin
Gibberellins
Cytokinins
Abscisic Acid
Ethylene

These include auxin, gibberellin, and cytokinin enhancers (Growth Promoters), while abscisic acid and ethylene are growth inhibitors.

5. Under what conditions can the seed be preserved? [S.S.C. Online Stenographer 14.09.2017 (Shift-I)]

(a) cold and moist conditions
(b) hot and dry conditions
(c) cold and dry conditions
(d) hot and humid conditions

Correct Answer: (c) cold and dry conditions

Solution:Cold and dry conditions -
Seeds are best preserved under cold and dry conditions. Low temperatures slow down metabolic processes, and low moisture content prevents the activation of enzymes and the growth of microorganisms that can damage the seed.

6. Which part of a plant cell traps sunlight to make sugar? [S.S.C. Online CHSL (T-I) 18.03.2020 (Shift-III)]

(a) Starch grain
(b) Chloroplast
(c) Chromoplast
(d) Leucoplast

Correct Answer: (b) Chloroplast

Solution:Chloroplast -
Chloroplasts are the organelles within plant cells that contain chlorophyll, the pigment that traps sunlight to carry out photosynthesis and produce sugars.

7. The process of generating energy in trees is known as _____ . [S.S.C. Online CHSL (T-I) 8.01.2017 (Shift-I)]

(a) absorption
(b) Reduction
(c) photosynthesis
(d) evaporation

Correct Answer: (c) photosynthesis

Solution:Photosynthesis -
Photosynthesis is the primary process by which trees, being plants, convert light energy into chemical energy (sugars) to fuel their growth and other life processes.

8. Which is the only major process through which oxygen is returned to the atmosphere? [S.S.C. Online MTS (T-I) 5.10.2017 (Shift-I)]

(a) Combustion
(b) Respiration
(c) Formation of oxides of nitrogen
(d) Photosynthesis

Correct Answer: (d) Photosynthesis

Solution:Photosynthesis -
Photosynthesis is the only major biological process that releases oxygen into the atmosphere as a byproduct. Respiration and combustion consume oxygen.

9. Which of the following wavelengths of light is absorbed the most for photosynthesis? [S.S.C. Online MTS (T-I) 5.10.2017 (Shift-II)]

(a) White light
(b) Blue light
(c) Green light
(d) Orange light

Correct Answer: (b) Blue light

Solution:

Blue light -
Chlorophyll absorbs light most strongly in the blue and red regions of the electromagnetic spectrum. Therefore, blue light is highly effective in driving photosynthesis.

10. Which part of the plant synthesizes food? [S.S.C. Online MTS (T-I) 18.09.2017 (Shift-I)]

(a) leaves
(b) Roots
(c) stem
(d) flowers

Correct Answer: (a) leaves

Solution:The leaves of plants synthesize food. They absorb solar energy and form carbohydrates by taking in carbon dioxide from the air and water absorbed from the soil and take out oxygen in the form of hiccups.