List of top Biology Questions

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.

Enlist three advantages of genetically modified plants.
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 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.


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.

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.
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 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.
(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.
Name any two VDs which might occur in a human female. State any two complications in a female if it is left untreated.

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.

Give an account of the generalised structure of an antibody molecule produced by B-lymphocytes in response to the pathogen.
Explain what is meant by the term amniocentesis. How is this technique misused in India?
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:
What would happen if a gene encoding a polypeptide of 50 amino acids, $25^th$ Codon (UAU) is mutated to “UAA”?

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.
Study the pedigree chart given below, showing the inheritance pattern of blood group in a family:
pedigree chart
Answer the following questions:

[(a)] Give the possible genotypes of individual 1 and 2.
[(b)] Which antigen or antigens will be present on the plasma membranes of the R.B.Cs of individuals ‘5’ and ‘8’?
Study the diagram given below and answer the questions that follows:
nucleosome
(a) Identify the structure shown in the above figure.
(b) Identify the labels P and Q.
(c) Write the nature of histone proteins.
(d) Distinguish between Euchromatin and Heterochromatin.
(A)

Distinguish between the two cells enclosed in a mature male gametophyte of an angiosperm.
Study the diagram given below showing the modes of pollination. Answer the questions that follow.
modes of pollination


The given diagram shows three methods of pollen transfer in plants. Examine them carefully and write the technical terms used for pollen transfer methods ‘1’, ‘2’ and ‘3’.
How do the following plants achieve pollination successfully?

Water lily
Vallisneria
Write advantages of pollen transfer in method ‘3’. \begin{center} OR \end{center} (B)

Given below is the diagram of human ovum surrounded by a few sperms. Observe the diagram and answer the questions that follow:
human ovum surrounded by a few sperms


Compare the fate of sperms ‘P’, ‘Q’ and ‘R’ shown in the diagram.
Write the role of Zona pellucida in this process.
Analyse the changes occurring in the ovum after the entry of sperm.
How acrosome and middle piece of a human sperm are able to play an important role in human fertilization?
(A) Answer the following questions:

State what do you understand by “MALT”? Where is it located inside our body?
Explain cytokine barriers.
Name the diagnostic test for AIDS. On what principle does it work?
Bone marrow and thymus play an important role in human immune system. Explain how are they able to achieve this. \begin{center} OR \end{center} (B)

Study the following table \& fill ‘H’, ‘T’, ‘J’, ‘K’, ‘L’ and ‘M’ in the following table with suitable words:

Why are baculoviruses used as biological control agents?
(A)

Perform a cross between two sickle cell carriers. What ratio is obtained between carrier, disease free and diseased individuals in \( F_1 \) progeny? Name the nitrogenous base substituted, in the haemoglobin molecule in this disease.
Explain the difference in inheritance pattern of flower colour in garden pea plant and snap-dragon plant with the help of monohybrid crosses. \begin{center} OR \end{center} (B) Explain with the help of well-labelled diagrams how lac operon operates in \textit{E. coli} :

In presence of an inducer.
In absence of an inducer.
Study a part of life cycle of \textit{Plasmodium} given below:
life cycle of Plasmodium
Answer the following questions:
(a) Name the infective stage of \textit{Plasmodium} that is stored in the female \textit{Anopheles} mosquito.
(b) Where does fertilization and development of parasite take place?
(c) Identify labels P and Q in the given diagram.
(d) Asexual and sexual phase of the life cycle of the \textit{Plasmodium} takes place in two different hosts. Write their names.