Preparatory_CA_Biology
  • 1. The main reason why transport is necessary in a large plant is that
A) plants cannot lose water through their leaves
B) photosynthesis occurs only in the roots
C) mineral salts are produced in the leaves
D) all plant cells are unable to absorb substances directly from the environment
  • 2. Water enters a root-hair cell from the soil mainly because
A) the water potential of the cell sap is higher than that of the soil solution
B) water is actively pumped into the root hair
C) the soil solution contains more solutes than the cell sap
D) the water potential of the cell sap is lower than that of the soil solution
  • 3. Which process is primarily responsible for the uptake of water by root hairs?
A) Active transport
B) Transpiration
C) Osmosis
D) Translocation
  • 4. A plant absorbs mineral ions from the soil when their concentration in the soil is lower than that in the root-hair cell. This is possible mainly through
A) transpiration
B) active transport
C) osmosis
D) cohesion
  • 5. Which feature of a root-hair cell is most directly responsible for its efficient absorption of water?
A) Thick waxy cuticle
B) Absence of a cell membrane
C) Small vacuole
D) Large surface area
  • 6. Which sequence correctly represents the movement of water from the soil into the xylem?
A) Soil ---> cortex ---> root hair ---> endodermis ---> xylem
B) Soil ---> root hair ---> cortex ---> endodermis ---> xylem
C) Soil ---> epidermis ---> phloem ---> endodermis ---> xylem
D) Soil ---> root hair ---> phloem ---> cortex ---> xylem
  • 7. The tissue mainly responsible for transporting water and mineral salts from the roots to the leaves is the
A) epidermis
B) xylem
C) cambium
D) phloem
  • 8. Which pair of substances is transported mainly through the xylem?
A) Glucose and fatty acids
B) Starch and proteins
C) Sucrose and amino acids
D) Water and mineral salts
  • 9. The major force responsible for pulling water upwards through the xylem of a tall plant is
A) root pressure
B) atmospheric pressure
C) transpiration pull
D) active transport by xylem cells
  • 10. Transpiration is the
A) loss of water vapour from the aerial parts of a plant
B) movement of water through the xylem
C) loss of liquid water from the roots
D) absorption of water from the soil by roots
  • 11. The greatest proportion of water lost from the leaves of most plants occurs through the
A) stomata
B) veins
C) cuticle
D) lenticels
  • 12. Which combination of conditions would normally produce the highest rate of transpiration?
A) Low temperature, high humidity and weak wind
B) Low temperature, high humidity and strong wind
C) High temperature, low humidity and strong wind
D) High humidity, low temperature and darkness
  • 13. An increase in atmospheric humidity usually reduces transpiration because it
A) causes the xylem vessels to close
B) increases the concentration of water vapour inside the leaf
C) increases the temperature of the leaf
D) reduces the water-vapour concentration gradient between the leaf and atmosphere
  • 14. Strong wind generally increases the rate of transpiration because it
A) reduces the surface area of the leaf
B) closes all the stomata permanently
C) removes the layer of humid air surrounding the leaf
D) increases the water potential of the leaf
  • 15. Which of the following is an external factor affecting transpiration?
A) Leaf area
B) Atmospheric humidity
C) Number of stomata
D) Thickness of the cuticle
  • 16. Which of the following is an internal factor affecting the rate of transpiration?
A) Number and distribution of stomata
B) Atmospheric humidity
C) Wind speed
D) Temperature
  • 17. If a leafy plant is placed in darkness for several hours, its rate of transpiration will generally decrease because
A) its xylem vessels become blocked
B) its leaves immediately lose their cuticle
C) its root hairs stop absorbing water completely
D) its stomata tend to close
  • 18. Which statement correctly distinguishes the three types of transpiration?
A) Stomatal occurs through lenticels, cuticular through stomata and lenticular through roots
B) Stomatal occurs through roots, cuticular through xylem and lenticular through phloem
C) Stomatal occurs through stomata, cuticular through the cuticle and lenticular through lenticels
D) All three types occur only through stomata
  • 19. A potometer is an apparatus used primarily to
A) measure the amount of food transported through the phloem
B) measure the amount of water produced during photosynthesis
C) estimate the rate of transpiration by measuring water uptake
D) determine the concentration of mineral salts in the soil
  • 20. In an experiment using a potometer to investigate the effect of wind speed on water uptake, the dependent variable is the
A) rate of water uptake
B) size of the leafy shoot
C) distance between the plant and fan
D) wind speed
  • 21. A bubble in a potometer moves 6 cm in 3 minutes. What is the average rate of movement of the bubble?
A) 3 cm/min
B) 18 cm/min
C) 2 cm/min
D) 6 cm/min
  • 22. Why should the leafy shoot be cut under water before being attached to a potometer?
A) To increase the rate of photosynthesis
B) To prevent water entering the shoot
C) To remove mineral salts from the xylem
D) To prevent air entering and blocking the xylem
  • 23. Which precaution would improve the accuracy of a potometer experiment?
A) Leave the joints loosely connected
B) Allow air bubbles to remain in the xylem
C) Remove all the leaves from the shoot
D) Ensure the apparatus is airtight
  • 24. A potometer does not measure transpiration directly because it
A) measures water uptake, which is used as an estimate of water loss
B) measures the amount of water stored in the leaves
C) measures only water absorbed by the roots
D) measures only the amount of water lost through the cuticle
  • 25. Which of the following is an important advantage of transpiration?
A) It prevents cooling of the leaves
B) It creates a transpiration pull that assists water movement through the plant
C) It prevents all water loss from the plant
D) It stops mineral salts from entering the roots
  • 26. Excessive transpiration may result in
A) increased water content of the leaves
B) permanent closure of the xylem vessels
C) wilting because water loss exceeds water absorption
D) increased turgidity of all cells
  • 27. The upward movement of water in the xylem is assisted by transpiration because
A) evaporation of water from leaves creates a pull on the continuous water column
B) water vapour is actively pumped into the xylem
C) stomata push water downwards into the roots
D) transpiration produces water in the leaves
  • 28. Translocation in plants refers to the movement of
A) water and mineral salts through the xylem from roots to leaves
B) manufactured food through the phloem from source to sink
C) oxygen through the intercellular spaces of the leaf
D) water through the stomata into the atmosphere
  • 29. According to the mass-flow hypothesis, movement of sucrose through the phloem occurs mainly because
A) loading of sugars at the source causes water to enter the phloem, creating pressure that drives sap towards the sink
B) xylem vessels actively pump sucrose into the phloem
C) water evaporates from the phloem and pulls sucrose towards the roots
D) sugars move only by diffusion from the roots to the leaves
  • 30. In a ringing experiment, a complete ring of bark is removed from around the stem of a woody plant while the xylem remains intact. After some time, food accumulates above the ring. This demonstrates that
A) mineral salts are transported through the phloem
B) manufactured food is transported through the phloem
C) manufactured food is transported through the xylem
D) water is transported through the phloem
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