List of top Biology Questions

(a) (i) Explain the structure of a typical monocotyledonous embryo of a flowering plant.
(ii) How are multiple embryos formed in a citrus fruit? What is the mechanism known as?

OR

(b) (i) Name and explain the structural organization of the male sex accessory ducts in the human male reproductive system.
(ii) Describe the role of gonadotropin FSH (Follicle-Stimulating Hormone) in the regulation of spermatogenesis.

Read the following passage and answer the questions that follow:
In 2021, 5.3 percent of 15 to 16-year-olds worldwide (13.5 million individuals) had used Cannabis in the past year according to UNODC. The adolescent brain is still developing and drug use can have long-term negative effects. Early drug use initiation can lead to faster development of dependence than in adults and other problems in adulthood. Parts of the Amazon Basin are at the intersection of multiple forms of organized crimes that are accelerating devastation, with severe implications for the security, health, and well-being of the population across the region. The direct impact of coca cultivation on deforestation is minimal, but indirectly it acts as a catalyst for "Narco-deforestation." The laundering of drug trafficking profits into land speculation etc. is posing a growing danger to the world's largest rainforest.

(a) Which age group or period of growth are people more vulnerable to drug abuse?

(b) Explain the negative impact of coca cultivation on the world's largest rainforest.

(c)
(i) From which part of the plant are cannabinoids mainly obtained? Mention any one negative effect of this drug on adolescents.
OR
(ii) State the scientific name of the plant from which coca alkaloids are derived and state one negative impact of the use of excessive dosage of cocaine.

Define transgenic animals. Explain in detail any four areas where they can be used for human benefit.

(a) (i) Describe the population growth curve applicable in a population of any species in nature that has unlimited resources at its disposal.
(ii) Explain the equation of this growth curve.
(iii) Name the growth curve and depict a graphical plot for this type of population growth.

OR

(b) (i) Explain the conclusion drawn by Alexander von Humboldt during his extensive explorations in the wilderness of South American jungles.
(ii) Give the equation of the Species-Area relationship.
(iii) Draw a graphical representation of the relation between species richness and area for a wide variety of taxa such as birds, bats, etc.

During a medical investigation, an infant was found to possess an extra copy of chromosome no. 21. Identify the disorder the child is suffering from. Describe the symptoms the child is likely to develop later in life.
Explain the neuroendocrine mechanism involved in the process of parturition in a human female leading to the expulsion of the baby out of the uterus through the birth canal.
Explain how the loss of habitat and fragmentation drives plants and animals to extinction with the help of an example of habitat loss in the Tropical Rain Forest. Also write the effect of fragmentation of a habitat on the population decline.

Many of the flowering plants producing hermaphrodite flowers have developed many devices to discourage self-pollination and to encourage cross-pollination. Given below is a picture of one such outbreeding device in a flowering plant. Study the picture and answer the questions that follow:

(a) Explain how the given type of pollination is advantageous to the plant.

(b) Can this flowering plant show geitonogamy? Justify your answer.


Study the diagram above and answer the following questions:
(a) How many alleles are involved in blood grouping?

(b) A person having 'AB' blood group has both dominant alleles. What is this inheritance type called?

(c) A man with 'A' blood group marries a woman with 'B' blood group. Can they have a child with 'O' blood group? Explain with the help of a cross.

(a) Write the full form of BOD.
(b) Define BOD. Explain how it is a measure of the organic matter present in the water body.
Enlist three advantages of genetically modified plants.
Correctly depict (also indicate the trophic level) and describe the ecological pyramid of number with 32 birds dependent on 20 insects feeding on one banyan tree.
Explain how the interaction between a fig tree and its tight one-to-one relationship with the pollinator species of wasp is one of the best examples of mutualism.
The basic scheme of the essential steps involved in the process of recombinant DNA technology is summarised below in the form of a flow diagram. Study the given flow diagram and answer the questions that follow: \begin{center} Step-1 \quad Plasmid DNA (cut using Restriction Enzyme EcoR I) \quad + \quad Foreign DNA (cut using Restriction Enzyme EcoR I)
$\downarrow$
DNA ligase
$\downarrow$
Step-2 \quad Recombinant DNA molecule
$\downarrow$
Step-3 \quad Transfer of recombinant DNA molecule to the host cell
$\downarrow$
Step-4 \quad Replication of recombinant DNA molecule in the host cell \end{center} (a) Name the specific enzyme that might have been used to make the multiple copies of foreign DNA before undergoing Step-1 of the process.
(b) How does the use of restriction enzyme EcoR I in Step-1 facilitate the action of DNA ligase to form the recombinant DNA molecule? Explain.
(c) Name the most commonly used host in the above process.
Give an account of the generalised structure of an antibody molecule produced by B-lymphocytes in response to the pathogen.
Name any two VDs which might occur in a human female. State any two complications in a female if it is left untreated.
Other than public awareness and counselling, enlist four measures taken up by NACO, WHO and other NGOs to prevent the spread of HIV infection in the society.

Given below are the diagrammatic representations of the replicating fork of DNA in E. coli. Study the diagrams and answer the questions that follow.

(a) Which one of the three diagrams (i), (ii) or (iii) is the correct representation of the replicating fork of DNA replication? Explain your answer.
(b) Name the enzyme used in E. coli to join the newly synthesised fragments of DNA.

Explain what is meant by the term amniocentesis. How is this technique misused in India?
What would happen if a gene encoding a polypeptide of 50 amino acids, $25^th$ Codon (UAU) is mutated to “UAA”?
The correct depiction of the centrifugation step of the experiment conducted by Alfred Hershey and Martha Chase on using radioactive labelled phages to prove that DNA is the genetic material is:

Which of the following combinations is a correct example of convergent evolution in Australian marsupials and placental mammals?

Given below are few statements with reference to the uterus in the female reproductive system:
Mention the number of chromosomes at each stage. Correlate the life phases of the individual with the stages of the process.
Using a Punnett square, work out the distribution of an autosomal phenotypic feature in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.