Question 11:
Which process describes the movement of ions against their concentration gradient in plant cells?
A) Passive transport
B) Active transport
C) Diffusion
D) Osmosis
Answer: B) Active transport
Explanation: Active transport is the process by which ions are moved against their concentration gradient, requiring energy, usually in the form of ATP. This is crucial for nutrient uptake in plants.
Question 12:
Which of the following is NOT a function of water in plants?
A) Photosynthesis
B) Structural support
C) Nutrient transport
D) Energy storage
Answer: D) Energy storage
Explanation: Water is essential for photosynthesis, structural support, and nutrient transport, but it does not function as an energy storage molecule. Energy in plants is stored in the form of carbohydrates.
Question 13:
The primary method of sugar transport in plants is through:
A) Xylem
B) Phloem
C) Parenchyma
D) Sclerenchyma
Answer: B) Phloem
Explanation: Phloem is responsible for transporting sugars and other organic nutrients from the leaves (where they are produced) to other parts of the plant.
Question 14:
Which of the following environmental factors can increase the rate of transpiration?
A) High humidity
B) Low temperature
C) High wind speed
D) Abundant soil moisture
Answer: C) High wind speed
Explanation: High wind speed increases transpiration rates by moving moisture-saturated air away from the leaf surface, allowing more water to evaporate.
Question 15:
The primary tissue responsible for photosynthesis in leaves is:
A) Epidermis
B) Xylem
C) Phloem
D) Mesophyll
Answer: D) Mesophyll
Explanation: Mesophyll tissue in leaves contains chloroplasts where photosynthesis takes place, converting light energy into chemical energy.
Question 16:
Which of the following conditions would most likely lead to stomatal closure?
A) High light intensity
B) Low atmospheric humidity
C) High temperature
D) Abundant water supply
Answer: B) Low atmospheric humidity
Explanation: Low humidity can lead to increased water loss from the leaf, prompting stomata to close to conserve water.
Question 17:
Root pressure is most prominent in:
A) Trees
B) Herbaceous plants
C) Shrubs
D) Aquatic plants
Answer: B) Herbaceous plants
Explanation: Root pressure is more prominent in herbaceous (non-woody) plants, where it can help push water upward through the plant, especially at night.
Question 18:
In plants, the movement of water and nutrients is primarily facilitated by:
A) Diffusion alone
B) Active transport alone
C) Both diffusion and active transport
D) Only through xylem
Answer: C) Both diffusion and active transport
Explanation: Water and nutrient movement involves both passive processes like diffusion and active processes that require energy, such as active transport.
Question 19:
The pressure flow hypothesis explains the movement of:
A) Water in xylem
B) Nutrients in phloem
C) Gases in stomata
D) Minerals in soil
Answer: B) Nutrients in phloem
Explanation: The pressure flow hypothesis describes how sugars are actively transported into the phloem, creating a pressure gradient that facilitates the flow of nutrients throughout the plant.
Question 20:
Which type of transport is mainly involved in the uptake of water by root hairs?
A) Active transport
B) Facilitated diffusion
C) Osmosis
D) Bulk flow
Answer: C) Osmosis
Explanation: Osmosis is the passive movement of water across a semi-permeable membrane from an area of low solute concentration to high solute concentration, which is how water is primarily absorbed by root hairs.
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