CBSE Questions for Class 12 Medical Biology Organisms And Population Quiz 7 - MCQExams.com

• In the given condition, the type of population growth curve will be S-shaped which is called a sigmoid curve.
• This type of growth curve represents that on introduction to a new area, the population grows slowly in the beginning followed by a sharp exponential increase in the growth rate.
• This is further followed by the stationary growth phase where the population is maintained at the constant level.
• This means that once a population achieves a maximum value it becomes stable where the growth rate is equal to the death rate.

• Viscum album grows on the tree to obtain water and nutrients. Association of organisms that benefits one of the partners at the expense of others is called parasitism. 
• Predation refers to feeding on other living organisms.
• Symbiosis is an association of organisms wherein both is benefitted while one organism is benefitted and the other remains unaffected in commensalism. 

• Mutualism or symbiosis is a mutually beneficial relationship between individuals of two different species. 
• It is a symbiotic association between two organisms in which both are benefited.
• None of the two is capable of living separately. Mutualism or symbiosis is generally considered to be obligatory. 
• For example, nitrogen fixing Rhizobium bacteria living in root nodules of leguminous plants. 
• Thus, the correct answer is option A.

• A behavior that reduces the fitness of the doer and increases the fitness of the recipient is said to be altruistic. 
• There is no direct benefit involved in this to the doer. However, there are indirect genetic benefits in which the organism with better traits is taken care of. 
• Since the individual takes care of the population it inherits the breeding population. 
• Also, the number of offsprings are less . Hence the species will be benefited from reduced competition for food, territory and other resources. Thus the correct answer is option C.

• Commensalism refers to a relationship wherein one organism is benefitted while others remain unaffected. 
• Predation refers to the act of feeding on other animals. 
• Competition refers to the struggle for the same resource between the organisms. 
• Mutualism is an association of organisms wherein both are benefitted. 

• Density of the population is a number of individuals per unit of area or per unit of volume. It is calculated as a population divided by total land area or water volume. 
• There are different factors which affects population density such as natality rate, mortality rate, emigration, immigration, age distribution, carrying capacity.
• Natality rate and immigration increase population density whereas mortality rate and emigration decreases population density.

A. Ascending straight line – the graphical representation of the increase in growth. it is the representation of the growth of bacteria per minute.

B.Sigmoid – Graphical representation of the growth of an organism.

C.Hyperbolic – Graphical representation of the effect of environmental factors on enzymes.

D. Descending straight line – The graphical representation of decrease in growth of the organisms.

The graphical representation of the growth of bacteria is Ascending straight line. It shows Lag, log, decline and stationary stage.

• The majority of animals cannot regulate their body temperature with the change in environment. 
• Thermoregulation is expensive for most of the organisms, especially smaller organisms. 
• As heat gain and loss depend on the surface area, small animals have more surface area relative to volume, so they lose more body heat. 
• This is why small animals are hardly found in polar regions.
• Shivering is a kind of exercise which produces heat and raises body temperature.
  
• Diapause is a stage of suspended development seen in zooplankton.
  
• So, the correct answer is option D.

• The exponential equation for population growth is given by :

• Various environmental factors can be divided majorly into climatic factors, edaphic factors and biotic factors.
  
• The factors which relate to structure and composition of soil are called edaphic factors. Soil composition, organic matter, soil water, soil air and soil organisms are examples of edaphic factors.
• Humidity, rainfall, and wind velocity are climatic factors.
• Examples of biotic components include animals, plants, fungi, and bacteria.
  

The graph is called Growth curve. The graphical representation of growth as a function of time is called Growth curve. It is used in statistics to determine the type of growth pattern quantity is it linear, exponential or cubic.  Its shows three phases, Lag phase, Log phase and Stationary phase.