Question 91:
The concept of “carrying capacity” refers to:
(A) The maximum number of species an ecosystem can support
(B) The number of prey animals in an ecosystem
(C) The maximum number of individuals of a species that an environment can sustain indefinitely
(D) The reproductive rate of a species
Answer: (C) The maximum number of individuals of a species that an environment can sustain indefinitely
Explanation:
Carrying capacity is the maximum population size of a species that an environment can support indefinitely, given the available resources such as food, water, and habitat space.
Question 92:
Which of the following is a major cause of biodiversity loss?
(A) Habitat destruction
(B) Conservation programs
(C) Sustainable farming practices
(D) Ecotourism
Answer: (A) Habitat destruction
Explanation:
Habitat destruction, caused by activities such as deforestation, urbanization, and agriculture, is a major cause of biodiversity loss. It leads to the displacement and extinction of species as their natural environments are disrupted or destroyed.
Question 93:
Which of the following is an example of mutualism?
(A) Bees pollinating flowers
(B) A lion hunting a deer
(C) A tapeworm living in a human intestine
(D) A bird nesting in a tree
Answer: (A) Bees pollinating flowers
Explanation:
Mutualism is a symbiotic relationship where both organisms benefit. Bees pollinate flowers while collecting nectar, which benefits both the bees (as food) and the flowers (as pollination). The other options represent other types of relationships, such as predation or parasitism.
Question 94:
Which of the following is a secondary consumer in a food chain?
(A) Grasshopper
(B) Deer
(C) Frog
(D) Algae
Answer: (C) Frog
Explanation:
Secondary consumers feed on primary consumers (herbivores). Frogs, which feed on insects, are secondary consumers. Grasshoppers are primary consumers, deer are also primary consumers, and algae are primary producers.
Question 95:
What role do lichens play in primary succession?
(A) They accelerate soil erosion
(B) They are the first organisms to colonize bare rock and begin the process of soil formation
(C) They are secondary consumers
(D) They prevent the growth of other plants
Answer: (B) They are the first organisms to colonize bare rock and begin the process of soil formation
Explanation:
Lichens are pioneer species in primary succession. They can colonize bare rock, secrete acids that break down the rock, and begin the process of soil formation, allowing other plants to eventually grow.
Question 96:
Which of the following ecosystems is primarily characterized by its permafrost?
(A) Tropical rainforest
(B) Desert
(C) Tundra
(D) Grassland
Answer: (C) Tundra
Explanation:
The tundra biome is characterized by its permafrost, a layer of permanently frozen soil. This biome has very cold temperatures, limited vegetation, and a short growing season.
Question 97:
Which of the following organisms is a tertiary consumer?
(A) Grass
(B) Rabbit
(C) Hawk
(D) Cow
Answer: (C) Hawk
Explanation:
A hawk is a tertiary consumer because it feeds on secondary consumers, such as small mammals or birds, which are themselves carnivores or omnivores. Grass and rabbits are part of the lower trophic levels, and cows are herbivores (primary consumers).
Question 98:
Which of the following gases is primarily responsible for the depletion of the ozone layer?
(A) Methane
(B) Chlorofluorocarbons (CFCs)
(C) Carbon dioxide
(D) Nitrous oxide
Answer: (B) Chlorofluorocarbons (CFCs)
Explanation:
CFCs are the main chemicals responsible for the depletion of the ozone layer. They break down ozone molecules in the stratosphere, leading to the formation of the ozone hole.
Question 99:
The term “trophic level” refers to:
(A) The number of organisms in a population
(B) The position of an organism in the food chain
(C) The total biomass in an ecosystem
(D) The rate of energy transfer in an ecosystem
Answer: (B) The position of an organism in the food chain
Explanation:
A trophic level represents the position an organism occupies in a food chain, such as producers (first level), herbivores (second level), and carnivores (higher levels).
Question 100:
Which of the following best describes the greenhouse effect?
(A) The trapping of heat in Earth’s atmosphere by greenhouse gases
(B) The reflection of solar radiation back into space
(C) The loss of heat from Earth’s surface
(D) The depletion of the ozone layer
Answer: (A) The trapping of heat in Earth’s atmosphere by greenhouse gases
Explanation:
The greenhouse effect refers to the process by which greenhouse gases, such as carbon dioxide and methane, trap heat in the Earth’s atmosphere, warming the planet. This is essential for maintaining life-supporting temperatures but can lead to global warming when excessive.
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