Organisms and Populations Test - 33

Population growth rate measures the number of individuals in a population (N) over time (t). When the conditions are ideal, the type of growth is known as exponential form of growth which is expressed by the equation, (dN)/(dt)= rN. When the limiting factors is restricted, the growth pattern is known as logistic growth model. This model is described by the differential equation (dN)/(dt)= rN(K-N)/K, where K is the carrying capacity and r is the maximum per capita growth. 

• Predation is a type of interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked). 
• Parasitism is a relationship between species, where one species, the parasite, benefits at the expense of the other, the host. 
• Symbiosis is the relationship between two or more organisms living closely together and cannot survive without each other. 
• Exploitative competition occurs when consumption of a limiting resource by one species that makes the resources unavailable for consumption by another. 

Thus, the correct answer is option A.

Answer is option C
Period of 1951-61: is termed as population explosion period. High birth rate, low mortality rate and better health facilities were reason for this.
Period of 1961-71: growth rate of population was 24.8%
Period of 1971-81: growth rate of population was 25%
Period of 1981-91: growth rate of population was 25.3%
Period of 1991-2001: growth rate of population was 26.9%.
Population of India increased to 102.70 crore in 2001. The main reason for this tremendous rise in population in the last 50 years was fall in death rate, advanced medical facilities and no fall in birth rate. Hence, the concave shaped growth curve is obtained.

Predation is an interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked). Parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Symbiosis is close and often long-term interaction between two different biological species. Commensalism is a class of relationships between two organisms where one organism benefits from the other without either harming or benefiting the latter.

When population B is increased the population A will decrease, both the population is competing for the same food (grass) and population B is better adapted and competed more successfully for food than population A did. Hence, the correct answer is option B.

The forest ecosystem has the largest total biomass, which represents about 70% of the whole terrestrial ecosystem. The desert ecosystem has minimum biomass value.

Forests are called dynamic living entity. This is because they constitute a wide variety of biodiversity of flora and fauna residing in them. So, option B is the correct answer.

A.Correct option: D

B.Explanation for the correct option.

• Epiphytes are air plants that grow on other plants. They are not anchored in the soil and use rainwater and air as a source of nutrition. They are found in moist tropical areas. Prairie is a grassland of North America where trees and tall shrubs are rare to find and so for this reason epiphytes are not found in the prairie.

   Explanation for incorrect pairs:

   Option (A): Acacia trees are very common in the savanna. The fire-resistant feature of their long taproots helps them survive the drought conditions in the savanna. 
  Option (B): Coniferous forests consist mostly of conifers that tend to be evergreen. Evergreen plants have foliage that remains green and functional for more than one growing season. 

  Option (C): Tundra is a treeless polar desert with long and dry winters. Permafrost is any ground that remains frozen. It is a common feature of the tundra