Class 12 Biology 2023 Board Exam

A human ovum completes its second meiosis :
[Max Marks: 1 | Set: 57/1/3]

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.
[Max Marks: 1 | Sets: 57/3/1, 57/3/2, 57/3/3]

Which one of the following processes results in the production of recombinants in future generations ?
(i) Mutation
(ii) Independent assortment during meiosis I
(iii) Independent assortment during meiosis II
(iv) Crossing over of bivalents
[Max Marks: 1 | Set: 57/1/1]

Three genes R, S and T are located on the same chromosome. If the recombinant percentage between R and S is 20%, R and T is 35% and S and T is 15% respectively, can you predict the correct order of these genes on the chromosome ? Which of the following shows the correct sequence of the genes on the chromosome ?
[Max Marks: 1 | Set: 57/1/2]

Choose the set of sex determining chromosomes that indicates the correct sex of the respective organism.
[Max Marks: 1 | Set: 57/3/1]

Which of the following statements are true about the males in a colony of honey bees ?
(i) They have 16 chromosomes per cell.
(ii) They produce sperms by meiosis.
(iii) They have a grandfather but no father.
(iv) All males in the colony are haploid except one.
[Max Marks: 1 | Set: 57/3/2]

Choose the option that gives the correct number of pollen grains that will be formed after 325 microspore mother cells undergo microsporogenesis.
[Max Marks: 1 | Sets: 57/1/1, 57/1/2, 57/1/3]

Which of the following structures is well-developed in a mature seed of black pepper ?
[Max Marks: 1 | Set: 57/3/3]

Identify the region 'X', the factor 'Y' and the enzyme 'Z' involved in the process of transcription in prokaryote as shown in the schematic representation given below.
Region 'X' | Factor 'Y' | Enzyme 'Z'
[Max Marks: 1 | Sets: 57/1/1, 57/1/2, 57/1/3]

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 (N14 DNA and N15 DNA).
(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.
[Max Marks: 1 | Sets: 57/3/1, 57/3/2]