“Xerophytes: Adaptations to Dry Environments”
1. What are xerophytes?
A) Plants adapted to wet conditions
B) Plants adapted to dry conditions
C) Plants adapted to moderate conditions
D) Plants that lack chlorophyll
Answer: B) Plants adapted to dry conditions
Explanation: Xerophytes are plants that have evolved adaptations to survive in arid or semi-arid environments.
2. Which of the following is an example of a xerophyte?
A) Cactus
B) Fern
C) Lotus
D) Pine
Answer: A) Cactus
Explanation: Cacti are xerophytes that store water in their tissues to survive in dry environments.
3. What is the primary function of thick cuticles in xerophytes?
A) Gas exchange
B) Water retention
C) Nutrient absorption
D) Photosynthesis
Answer: B) Water retention
Explanation: Thick cuticles reduce water loss by minimizing evaporation from the leaf surface.
4. Why do xerophytes have spines instead of leaves?
A) To deter herbivores
B) To minimize water loss
C) For efficient photosynthesis
D) To improve reproduction
Answer: B) To minimize water loss
Explanation: Spines reduce surface area and help conserve water, an essential adaptation for survival in arid environments.
5. Which type of root system is common in xerophytes?
A) Shallow roots
B) Deep taproots
C) Fibrous roots
D) Aerial roots
Answer: B) Deep taproots
Explanation: Deep taproots allow xerophytes to access underground water sources in arid conditions.
6. What is CAM photosynthesis in xerophytes?
A) A type of respiration
B) A process of nocturnal gas exchange
C) A water storage mechanism
D) A reproductive strategy
Answer: B) A process of nocturnal gas exchange
Explanation: CAM photosynthesis allows xerophytes to fix carbon dioxide at night, reducing water loss during the day.
7. How do succulents store water?
A) In their roots
B) In their stems and leaves
C) In their flowers
D) In their seeds
Answer: B) In their stems and leaves
Explanation: Succulents store water in specialized tissues in their stems and leaves for use during droughts.
8. What role do hairy leaf surfaces play in xerophytes?
A) Attracting pollinators
B) Reducing water loss
C) Absorbing more sunlight
D) Increasing transpiration
Answer: B) Reducing water loss
Explanation: Hairy surfaces trap moisture and reduce the rate of water evaporation.
9. Which plant structure reduces transpiration in xerophytes?
A) Stomata
B) Trichomes
C) Cuticle
D) All of the above
Answer: D) All of the above
Explanation: Xerophytes use stomata regulation, trichomes, and thick cuticles to minimize water loss.
10. What is the primary purpose of sunken stomata in xerophytes?
A) Gas exchange
B) Water storage
C) Reducing water loss
D) Nutrient absorption
Answer: C) Reducing water loss
Explanation: Sunken stomata reduce the exposure to air, thereby decreasing transpiration.
11. How do rolled leaves benefit xerophytes?
A) Improve photosynthesis
B) Trap moisture
C) Increase nutrient absorption
D) Attract pollinators
Answer: B) Trap moisture
Explanation: Rolled leaves create a humid microenvironment, reducing water loss.
12. Which hormone aids xerophytes in surviving drought?
A) Gibberellin
B) Abscisic acid
C) Auxin
D) Cytokinin
Answer: B) Abscisic acid
Explanation: Abscisic acid helps regulate water balance and stomatal closure during drought.
13. Why do xerophytes often have waxy coatings on their leaves?
A) To attract insects
B) To repel water
C) To reduce water loss
D) To improve photosynthesis
Answer: C) To reduce water loss
Explanation: Waxy coatings help to minimize water evaporation from leaf surfaces.
14. What is the role of lignified tissues in xerophytes?
A) Transport nutrients
B) Store water
C) Provide mechanical support
D) Reduce water loss
Answer: C) Provide mechanical support
Explanation: Lignified tissues provide strength and help xerophytes withstand arid conditions.
15. How do xerophytes prevent wilting in extreme drought?
A) By closing stomata
B) By storing water in tissues
C) By reducing leaf size
D) All of the above
Answer: D) All of the above
Explanation: Xerophytes employ multiple strategies to conserve water and prevent wilting.
16. What are phreatophytes?
A) Plants with aerial roots
B) Plants that rely on surface water
C) Deep-rooted plants accessing groundwater
D) Plants with no roots
Answer: C) Deep-rooted plants accessing groundwater
Explanation: Phreatophytes are xerophytes with roots that reach deep underground water sources.
17. Which plant is a classic example of a xerophyte?
A) Bamboo
B) Acacia
C) Hydrilla
D) Mango
Answer: B) Acacia
Explanation: Acacia trees are xerophytes with adaptations for survival in arid environments.
18. How do xerophytes adapt to salty conditions in deserts?
A) Excreting salt
B) Storing salt in vacuoles
C) Thickening their cuticles
D) All of the above
Answer: D) All of the above
Explanation: Xerophytes use various mechanisms to survive saline conditions.
19. Which of the following plants uses CAM photosynthesis?
A) Wheat
B) Aloe vera
C) Rice
D) Oak
Answer: B) Aloe vera
Explanation: Aloe vera uses CAM photosynthesis to minimize water loss during daytime.
20. What do reduced leaves in xerophytes help with?
A) Increased sunlight absorption
B) Reduced water loss
C) Increased transpiration
D) Enhanced reproduction
Answer: B) Reduced water loss
Explanation: Reduced leaves lower the surface area, decreasing water loss in dry environments.
21. Which structural adaptation is common in desert xerophytes?
A) Hollow stems
B) Dense root systems
C) Thick, fleshy leaves
D) Floating leaves
Answer: C) Thick, fleshy leaves
Explanation: Thick leaves store water and nutrients, essential for desert survival.
22. What are ephemerals?
A) Long-lived plants
B) Short-lived desert plants
C) Aquatic plants
D) Parasites
Answer: B) Short-lived desert plants
Explanation: Ephemerals grow quickly during favorable conditions and survive as seeds during drought.
23. Why do some xerophytes have no leaves?
A) To save energy
B) To conserve water
C) To attract pollinators
D) To store food
Answer: B) To conserve water
Explanation: Leafless xerophytes rely on their stems for photosynthesis and minimize water loss.
24. What is a common adaptation of cacti spines?
A) Water storage
B) Heat reflection
C) Predator defense
D) Gas exchange
Answer: C) Predator defense
Explanation: Spines deter herbivores while also reducing water loss.
25. What type of habitat do xerophytes typically inhabit?
A) Wetlands
B) Forests
C) Deserts
D) Oceans
Answer: C) Deserts
Explanation: Xerophytes are primarily found in arid and semi-arid desert environments.
