List of top Biology Questions

Answer the following questions:

(a) [(i)] Explain how some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans but do not kill the Bacillus.

[(ii)] How is the above mechanism exploited for the production of Bt cotton plant by biotechnologists?

(b) [(i)] Explain how the amplification of gene of interest is done using PCR.

[(ii)] State two applications of the desired amplified fragment of DNA.

Explain the beneficial role of the following, produced as a result of the processes of biotechnology, to mankind:
(a) Cow named Rosie
(b) \(\alpha\)-1-antitrypsin

Answer the following questions with respect to the sex determining mechanism observed in honey bee.

[(a)] Name the type of sex determination system observed in honey bee.
[(b)] Fill in the blanks (i), (ii) and (iii) in the given question.

[(c)] What will be the sex and chromosome number of the progeny formed from the unfertilised eggs of honey bee?

(a) What do you mean by activated sludge in an STP?
(b) Explain the biological treatment of the major part of the sludge transferred from the large aeration tank into the anaerobic sludge digesters before its final release into the natural water bodies.

(a) Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with the help of any two examples.
(b) State any two criteria for determining biodiversity hotspots.

(a) Name and explain the role of inner and middle walls of the human female uterus.
(b) Write the location and function of fimbriae in human female.

Study the given molecular structure of double-stranded polynucleotide chain of DNA and answer the questions that follow.

(a) How many phosphodiester bonds are present in the given double-stranded polynucleotide chain?
(b) How many base pairs are there in each helical turn of double helix structure of DNA? Also write the distance between a base pair in a helix.
(c) In addition to H-bonds, what confers additional stability to the helical structure of DNA?

Student to attempt either option (A) or (B):
(A) (i) Explain why the milk produced by the mother during the initial days of lactation is considered to be very essential for the newborn infant.
(ii) What is the term used for the milk produced during the initial days of lactation?
OR
(B) Many children in the metro cities are suffering from a very common exaggerated response of the immune system to certain weak antigens in air.
(i) What is the term used for the above mentioned disease?
(ii) Name the main type of antibody produced by the immune system in response to this disease.
(iii) Which two main inflammation-causing chemicals are produced by the mast cells in such an immune response?

Assertion (A): In humans, filariasis is characterized by inflammation in the lower limbs.
Reason (R): Filarial worm usually lives in the lymphatic vessels of the lower limbs.

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.

(a) What is the technical term used for Step 4 in the above process?
(b) Which of the given two combinations of restriction enzyme should be used in Step 1? Justify your answer.
(i) EcoR I to cut the plasmid and Hind III to cut the alien DNA.
(ii) EcoR I to cut both the plasmid and alien DNA.

Assertion (A): Male contraceptive ‘Nirodh’ works on the principle of avoiding chances of ovum and sperm meeting.
Reason (R): It is made of thin rubber/latex sheath and is used to cover the penis before coitus.

Assertion (A): In dihybrid crosses involving sex-linked genes in Drosophila generation of non-parental gene combinations are observed.
Reason (R): Two genes present on different chromosomes show linkage and recombination in Drosophila.

Assertion (A): Isolated single cells can be fused to produce somatic hybrids.
Reason (R): Cells selected for somatic hybridisation have desirable characters.

Select the statements that are true for the seed of angiosperm from the given options:
(i) Non-albuminous seeds have no residual endosperm.
(ii) Residual, persistent nucellus in wheat is known as perisperm.
(iii) Integuments of ovules harden as tough protective seed coat.
(iv) Metabolic activity of the embryo slows down in dormancy.
Choose the correct option:

A characteristic property that distinguishes a malignant tumor from a benign tumor is:

Bottled fruit juices are clearer as compared to those made at home, as they are clarified by the use of:

In his observations of small black birds in the Galapagos Islands, Darwin found that all the finches arose from the original ancestor:

Which of the following do \textit{not follow the law of independent assortment?

The cloning site present in the tetracycline resistance gene of \textit{E. coli cloning vector pBR322 is:

If a natural population with 50 individuals is in Hardy-Weinberg equilibrium for a gene with two alleles A and a, with the gene frequency of allele A of 0.6, the genotype frequency of Aa will be:

SNPs in Human Genome Project refers to:

Study the pedigree chart of a family sharing the inheritance of sickle cell anemia.

The trait traced in the above pedigree chart is:

The process of splicing in eukaryotes represents the dominance of the:

Given below are a few statements with respect to spermatogenesis in a human male.
(i) Sperms are released from the seminiferous tubules by the process of spermiation.
(ii) Spermiogenesis involves the maturation of spermatids into sperms.
(iii) Spermatogonia produce spermatids by the process of spermiogenesis.
(iv) Meiosis II in secondary spermatocytes results in the formation of four equal haploid spermatids.
(v) Primary spermatocyte completes the first meiotic division forming two equal, diploid cells called secondary spermatocytes.
Choose the option with all true statements from the given options:

Given below are few statements with reference to the ovaries of the human female reproductive system:
(i) It is 2--4 cm in length and is connected to the pelvic wall by tendons.
(ii) It is covered by a thin epithelium which encloses the ovarian stroma.
(iii) The stroma is divided into a peripheral medulla and an inner cortex.
(iv) The ovaries are the primary female sex organs that produce the female gamete (ovum).
(v) Ovaries are located one on each side of the lower abdomen.
Choose the option with all the true statements from the given options: