Organisms And Populations MCQs

Ans: 2) Plateau phase

Explanation: In the Plateau phase, the birth rate remains stationary so the natality rate is equal to the mortality rate. No more population growth, population size is constant. In this phase, the net change in the population becomes zero.

Ans: 3) Garden snail

Explanation: They prefer an undisturbed environment with enough moisture and food. A strong shell protects the snail's body, which is generally patterned with spirals. Although most land snails are nocturnal, they may emerge from their hiding places during the day after a shower. A long, flat, muscular organ called a foot allows them to move in a gliding motion.

Ans: 3) Survive subzero temperatures

Explanation: Antifreeze proteins (AFPs) are biological antifreeze molecules that were first discovered in polar fish. AFPs can attach to ice and hence prevent ice crystal development. Because of AFPs, fish may live in ice-covered or cold waters below the freezing point (0.7 °C) of their blood serum.

Ans: 1) Biotic community

Explanation: A biotic community, also known as a biota or 'biocoenosis,' is a group of organisms that share an environment or habitat and interact with one another. An ecosystem is made up of the biotic community and the physical landscape, or abiotic factors.

Ans: 2) Animals adapted to live in deserts

Explanation: A xerocole, sometimes known as a desert animal, is an animal that has evolved to live in the desert. They must overcome two major obstacles: a scarcity of water and extreme heat. They save water by avoiding evaporation and concentrating excretions.

Ans: 2) Animals that are adapted to burrowing

Explanation: Animals that dwell underground and dig tunnels and burrows are known as fossorial and subfossorial. Some of them are fully below, while others surface for a few hours during the day. The basal rate of the average fossorial animal is between 60% and 90%.

Ans: 1) Biotic Potential

Explanation: The unrestrained growth of populations that results in the population's maximum growth is referred to as biotic potential. The biotic potential is defined as a species' maximum conceivable vital index, or when the species has the highest birth rate and lowest mortality rate.

Ans: 2) Retain water

Explanation: Crassulacean acid metabolism (CAM) is a photosynthetic adaptation to intermittent water supplies found in arid-zone plants (such as cacti) and tropical epiphytes (e.g., orchids and bromeliads). During the day, CAM plants cover their stomata and absorb CO2 at night, when the air temperature is cooler.

Ans. 2) Spongy Parenchyma

Explanation: Xerophytes are plants that grow in areas with very little water and moisture. They are mostly found in arid and semi-desert environments. These plants have changed their physical structures to adapt to their environments, such as thickened cuticles, sunken stomata, and lengthy roots that reach deep into the soil.

Ans: 1) Resemblance between an organism and an object

Explanation: Mimicry is defined as a species' developed similarity to a living or non-living model,' such that a selection agent or 'dupe ', unable to discriminate between them, interacts with the mimic as it would with the model to the mimic's benefit.

Ans: 2) Exponential phase

Explanation: The log phase (also known as the logarithmic or exponential phase) is a period in which cells double in size. If growth is unrestricted, doubling will occur at a constant pace, resulting in a doubling of both the number of cells and the rate of population expansion with each passing period.

Ans: 3) Desert

Explanation: Days in the desert are extremely hot, and nights are extremely cold. Desert soil is far more vulnerable to these variations than soil in other regions due to sparse plant cover. The earth becomes hot throughout the day and cools down often at night. As a result, this choice is right because the temperature varies the greatest here.

Ans: 2) Hibernation

Explanation: Hibernation is a strategy for animals to store energy in order to survive harsh weather or a shortage of food. Physiological changes such as a reduction in body temperature and a reduced metabolism are involved. People may benefit from medical research into the processes involved in hibernation.

Ans: 4) Sharing resources between two species

Explanation: The partial or complete sharing of resources or other ecological characteristics (predators, foraging area, soil type, and so on) by two or more species is referred to as niche overlap. In community ecology, niche overlap is a crucial issue since it is thought to govern how many and which species may coexist in a community.

Ans: 3) Symbiotic relationship

Explanation: A symbiotic relationship between a green plant and a fungus is known as mycorrhiza. Photosynthesis produces organic compounds such as sugars, which the plant gives to the fungus, while the fungus gives the plant water and mineral nutrients from the soil, such as phosphorus.