Free Forms and Functions of Plants MCQs with Answers

171. Functional group of chlorophyll a:

• A. -CH3
• B. -CHO
• C. -COOH
• D. -OH

Explanation: Chlorophyll A is a bluish-green pigment that is soluble in organic solvents like acetone and alcohol. It's molecular formula is C55H72O5N4Mg. It is made up of a squarish tetrapyrrolic ring known as the head and a phytol alcohol known as the tail.

172. Chlorophyll molecule contains:

• A. Mg2+
• B. Ca2+
• C. K+
• D. Na+

Explanation: Mg2+ ions are essential in making chlorophyll similar to how iron ions are substantial in making haemoglobin. The Mg ions are found in the centre of the chlorophyll molecule.

173. The tail of chlorophyll molecule is embedded in:

• A. Membrane of mitochondria
• B. Thylakoid membrane
• C. Membrane of Smooth Endoplasmic Reticulum
• D. Membrane of Rough Endoplasmic Reticulum

Explanation: The thylakoid membrane of the chloroplasts has these light-harvesting clusters called photosystems which contain various pigments needed to absorb light. These pigments, including chlorophyll, have their tails embedded in the thylakoid membrane as both are hydrophobic. The head of the molecule acts as a solar panel, facing and absorbing light.

174. Carotenoids absorb light of:

• A. Yellow-orange range
• B. Yellow-red range
• C. Orange-red range
• D. Blue-violet range

Explanation: Carotenoids are one of the accessory pigments in the chloroplasts which absorb light in the Blue-Green and Violet range.

175. Chlorophyll 'a' and chlorophyll 'b' differ in one of the functional group. Chlorophyll 'a' has:

• A. -CHO
• B. -OH
• C. -CH3
• D. -NH2

Explanation: The only difference between chlorophyll-a and b is that chlorophyll-a has methyl (CH3) on the 2nd pyrrole ring and whereas chlorophyll-b has an aldehyde (-CHO) at this point.

176. Glycerate-3-phosphate in the presence of ATP and reduced NADP from light dependent stage is reduced to:

• A. 3-carbon compound
• B. Ribulose bisphosphate
• C. 5-carbon compound
• D. 6-carbon compound

Explanation: Glycerate-3-phosphate, being a carboxylic acid, gets reduced to glyceraldehyde phosphate which is a 3-carbon compound.

177. In plants, which sugar is transported from source to sink through sieve tubes?

• A. Glucose
• B. Sucrose
• C. Fructose
• D. None of the above

Explanation: Factual recall;Glucose is the monosaccharide, that makes up the disaccharide sucrose along with fructose, whereas sucrose is the form, in which sugar is transported from source to sink. Sucrose is broken down to its constituents and then used by tissue cells.

178. Given figure shows:

• A. Structure of a Lenticel
• B. Hydathode showing gaseous vapour exchange
• C. Fungus reproducing by spore formation
• D. Algae reproducing by spore formation

Explanation: The figure shows the structure of 'Lenticel', which facilitates gaseous exchange and transpiration. These are aerating pores in the bark of woody trees. These are surrounded by loosely arranged thin walled complementary cells, enclosing intercellular spaces for gaseous exchange.

179. The _ describes how water and dissolved chemicals are carried through the cell wall and intercellular gaps of plants.

• A. Apoplast Theory
• B. Symplast Theory
• C. Vacuolar Theory
• D. Cytoplasmic Theory

Explanation: The theory that describes how water and dissolved chemicals are carried through the cell wall and intercellular gaps of plants is called the **Apoplast Theory** (Option A).In the Apoplast Theory, water and solutes move through the non-living, porous spaces outside the plasma membrane (cell wall and intercellular spaces) without entering the living protoplasts of the cells. This pathway includes the cell walls, spaces between cells, and the plant's vascular tissue.The Symplast Theory (Option B), on the other hand, describes the movement of water and solutes through the living cytoplasm of the plant cells, where they pass from one cell to another through plasmodesmata.The Vacuolar Theory (Option C) and Cytoplasmic Theory (Option D) are not recognized theories related to the movement of water and dissolved chemicals in plants.

180. Autotrophic mode of nutrition in an organism depends upon:

• A. Saprotrophic mode
• B. Parasitic mode
• C. Photosynthesis mode
• D. Obligate mode

Explanation: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy, using carbon dioxide and water to produce glucose and oxygen. This process is vital for life on Earth, as it provides oxygen and is the foundation of the food chain. Autotrophic mode of nutrition in an organism depends upon the photosynthetic mode.