Q41. What type of plant root system is typically found in grasses?
a) Taproot system
b) Fibrous root system
c) Adventitious root system
d) Tuberous root system
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Correct Answer: b) Fibrous root system
Explanation: Grasses typically have a fibrous root system. This system consists of a network of thin, branching roots growing from the base of the plant. Fibrous roots are excellent for stabilizing the soil and efficiently absorbing water and nutrients from a wide area near the soil surface.
Q42. Which element is primarily responsible for the regulation of osmotic pressure in plant cells?
a) Nitrogen
b) Potassium
c) Calcium
d) Phosphorus
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Correct Answer: b) Potassium
Explanation: Potassium is primarily responsible for the regulation of osmotic pressure in plant cells. It plays a crucial role in maintaining cell turgor pressure and is essential for the opening and closing of stomata, enzyme activation, and energy transfer processes. Adequate potassium levels are essential for water balance and efficient photosynthesis.
Q43. What is the primary function of the flower in plants?
a) Photosynthesis
b) Support and anchorage
c) Reproduction
d) Nutrient storage
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Correct Answer: c) Reproduction
Explanation: The primary function of the flower in plants is reproduction. Flowers are the reproductive structures of angiosperms (flowering plants). They contain the male and/or female reproductive organs and facilitate pollination, which leads to the production of seeds. Flowers often attract pollinators with their color, shape, and scent.
Q44. Which process is used by parasitic plants to obtain nutrients from their host?
a) Photosynthesis
b) Chemotropism
c) Symbiosis
d) Haustorial absorption
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Correct Answer: d) Haustorial absorption
Explanation: Parasitic plants obtain nutrients from their host plants through a process called haustorial absorption. They have specialized structures known as haustoria that penetrate the host plant’s tissues and extract water and nutrients. Unlike symbiotic relationships, this relationship is generally harmful to the host plant.
Q45. What is the significance of seed dispersal in plants?
a) It promotes genetic diversity.
b) It aids in water absorption.
c) It increases sunlight exposure.
d) It enhances soil nutrition.
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Correct Answer: a) It promotes genetic diversity.
Explanation: Seed dispersal is significant in plants as it promotes genetic diversity and reduces competition among offspring. By dispersing seeds away from the parent plant, plants ensure that their offspring have a better chance of finding suitable growing conditions and reduce the likelihood of overcrowding and competition for resources such as light, water, and nutrients.
Q46. What is the primary purpose of thorns in some plants?
a) Attracting pollinators
b) Assisting in photosynthesis
c) Providing structural support
d) Protecting against herbivores
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Correct Answer: d) Protecting against herbivores
Explanation: The primary purpose of thorns in some plants is to protect against herbivores. Thorns are modified stems, leaves, or parts of leaves that are hard and pointed. They serve as a physical barrier and deter animals from eating the plant, thus playing a crucial role in the plant’s defense strategy.
Q47. In what form do plants absorb nitrogen from the soil?
a) Elemental nitrogen (N2)
b) Nitrate (NO3-) and ammonium (NH4+)
c) Nitrogen dioxide (NO2)
d) Amino acids
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Correct Answer: b) Nitrate (NO3-) and ammonium (NH4+)
Explanation: Plants absorb nitrogen from the soil primarily in the form of nitrate (NO3-) and ammonium (NH4+). These forms of nitrogen are produced from the breakdown of organic material or from chemical fertilizers. Nitrogen is essential for plant growth as it is a key component of chlorophyll, amino acids, and nucleic acids.
Q48. What adaptation allows succulent plants to survive in arid environments?
a) Deep taproots
b) Thick, fleshy leaves or stems
c) Large flowers
d) Tall growth to reach sunlight
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Correct Answer: b) Thick, fleshy leaves or stems
Explanation: Succulent plants have adapted to survive in arid environments by developing thick, fleshy leaves or stems that store water. These water-storing tissues help the plants withstand long periods without rainfall. Additionally, many succulents have other adaptations like waxy coatings and reduced leaf surface area to minimize water loss.
Q49. Which plant hormone is responsible for fruit ripening?
a) Auxin
b) Gibberellin
c) Cytokinin
d) Ethylene
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Correct Answer: d) Ethylene
Explanation: Ethylene is a plant hormone responsible for fruit ripening. It is a gaseous hormone that stimulates the ripening process, leading to changes in fruit texture, softening, color, and the development of flavor and aroma. Ethylene production increases significantly in fruits during the ripening stage.
Q50. What is a distinguishing feature of monocotyledonous plants?
a) Net-like leaf veins
b) Two seed leaves
c) Parallel leaf veins
d) Woody stems
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Correct Answer: c) Parallel leaf veins
Explanation: A distinguishing feature of monocotyledonous (monocot) plants is the presence of parallel leaf veins. Monocots typically have leaves where the veins run parallel to each other along the length of the leaf. Other characteristics include having one seed leaf (cotyledon), flower parts in multiples of three, and scattered vascular bundles in the stem.