CBSE Questions for Class 12 Medical Biology Organisms And Population Quiz 1 - MCQExams.com

The plant Yucca shows a mutualistic relationship with the moth Colpa aurea . Both can't complete their life cycle without each other. The moth lays its egg inside the ovarian cavity of the plant and in return, the plant gets pollinated as the moth visits another flower for laying eggs. Young seeds of Yucca are the source of food for the larvae of Moth. So, the correct answer is option 4.

Natality is the rate of production of new individuals per unit area of population per unit time. Simply it is called birth rate. So, the correct answer is option 4.

• Mutualism (Symbiosis) is a relationship, in which both the interacting organisms/partners are benefited from each other. 
• Predation is the consumption of one species (the prey) by another (the predator). 
• Parasitism is a host-parasite relationship in which one (parasite) is benefited while the other (host) is adversely affected, although not necessarily killed.
• Competition is the injurious effect of one organism on another because of the removal of some resource of the environment. This phenomenon can result in major fluctuations in the composition of the microbial population in the soil.

• Commensalism is a long-term biological interaction in which members of one species gain benefits while those of the other species neither benefit nor are harmed. 
• Amensalism is a type of biological interaction. It is an association between two organisms if different species where one is adversely affected and the other stays unaffected.
• Competition is an interaction between organisms or species in which both the organisms or species are harmed.
• Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey.
  
• So, the correct answer is 'a-iv-Q, b-iii-P, c-ii-S, d-i-R'
  

Parasites are those organisms which obtain their nutrition from hosts.These parasites maintain physical contacts with the host plant through haustoria which are parasitic roots. These structures penetrate into host tissue and make connections with the conducting elements of host and draw nourishment. The common example includes Cuscuta (Total Stem parasite) which is never green and consequently they have no power to prepare their own food. They get all their food supply from the host plants. Hence option B is correct.

• Abiotic components: These are non-living components of the environment and consist of two things, materials and energy (that may be light or chemical energy). Materials include land, air, water, minerals, salts, atmospheric gases, rainfall, temperature etc.
• Biotic components: These are living components of the environment and divided into autotrophic and heterotrophic components. An autotrophic component is the producers or green plants while heterotrophic component includes consumers (primary, secondary and tertiary consumers) and decomposers (microbes). Hence, all the given options are correct.

Population Density is defined as the number of people living per square km. As per the provisional population totals of Census 2011, the population density of India has been 382 persons per square kilometer. Population density in the United States was last measured at 34.86 in 2014, according to the World Bank. Therefore population density of developing country like India is more than developed country like the USA. So, the correct answer is option D.