CBSE 12 Biology Question Paper-2023 Set-3

The stage of human evolution in which man started using skins to protect his body and burying the dead

Interferons are proteins. In the human body, they are secreted by :

Select the option that gives the incorrect match of the pathogen with the characteristics of the disease caused by it

Some important qualities of a population that are not significant for an individual are:

The diagram below shows the different developmental stages of an organism. This diagram shows the developmental stages of a:

What is the diversity in a population of organisms of the same species called?

Which of the following is an example of adaptive radiation?

The quality of a population that represents the ratio of individuals in different age groups is called:

What is the total group of all species in a specific area called?

Which of the following is a correctly written binomial name?

Which of the following is a bacterium that performs nitrification?

The first clinical gene therapy was given to a four-year-old girl with:

Which of the following is true with respect to the process of polymerisation of DNA?

Name the phase of cell cycle when DNA replicates:

Which of the following is an example of an incomplete dominant trait?

When a DNA molecule with heavy nitrogen (N15) is replicated in a medium containing normal nitrogen (N14), what will be the composition of the DNA molecules after two generations?

The principle of gene therapy is to:

A student finds a plant whose flowers are brightly coloured and fragrant, and which produces a large amount of nectar. The student can conclude that this plant is pollinated by:

A couple has three daughters. The probability of them having a boy as a fourth child is:

The technique of growing plants in a nutrient solution, without soil, is known as:

Which of the following is a vestigial organ in humans?

A human male decides to adopt a surgical method for contraception. Identify the point in the diagram where a cut would be made and tied.

Choose the set of sex determining chromosomes that indicates the correct sex of the respective organism.

Given below is a list of steps Meselson and Stahl carried out in their experiment to prove that DNA replication is semi-conservative. Select the option that gives the correct sequence of steps followed by them. (i) Bacteria transferred to a N14 medium and sampled every 20 minutes. (ii) All bacteria contain hybrid DNA (N14DNA and N15DNA). (iii) Bacteria grown in N15 medium for many generations. (iv) All bacteria contain N15 DNA. (v) Bacteria contain either all N14 DNA or all hybrid DNA.