List of top Biology Questions

Disorder caused due to accumulation of amyloid proteins in CNS.
Immunity in our body is of two types: (i) Innate immunity and (ii) acquired immunity. Innate immunity is a non-specific defence mechanism, whereas acquired immunity is pathogen-specific; it is called specific immunity too. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are different types of antibodies produced in our body: they are IgA, IgE, IgG, IgC, and IgM. It shows primary response when it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen.

(d) How is active immunity different from passive immunity?

Immunity in our body is of two types: (i) Innate immunity and (ii) acquired immunity. Innate immunity is a non-specific defence mechanism, whereas acquired immunity is pathogen-specific; it is called specific immunity too. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are different types of antibodies produced in our body: they are IgA, IgE, IgG, IgC, and IgM. It shows primary response when it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen.

(c) The organ transplants are often rejected if not taken from suitable compatible persons. [(i)] Mention the characteristic of our immune system that is responsible for the graft rejection. [(ii)] Name the type of immune response and the cell involved in it.

The symptoms of malaria do not appear immediately after the entry of sporozoites into the human body when bitten by female Anopheles mosquito. Explain why it happens.
Mention any four strategies adopted by flowering plants to prevent self-pollination.
Assertion (A): Restriction endonuclease recognises palindromic sequence in DNA and cuts them. Reason (R): Palindromic sequence has two unique recognition sites PstI and PvuI recognised by restriction endonuclease.
Assertion (A): The number of white winged moths decreased after industrialisation in England. Reason (R): Effects of industrialisation were more marked in rural areas of England.
For commercial and industrial production of citric acid, which one of the following microbes is used?
Select the correct statement from the following biotechnological procedures:
The decrease in the T-Lymphocytes count in human blood will finally result in
Inner wall of microsporangia is:
Write any three differences between anther and ovule.
Which fruit has fibrous mesocarp?
Which of the following hormones is not synthesized by anterior pituitary gland?

Identify the correct labellings in the figure of a fertilised embryo sac of an angiosperm given below: 

Expand the term ZIFT.
What are vestigial organs?

Explain the events which occur within a female Anopheles mosquito after it has sucked blood from a malaria patient.

With reference to flower color, two independent crosses were made, one between true breeding garden pea plants and another between true breeding Antirrhinum plants. Write the phenotypes of their F$_1$ progeny. Justify your answer giving reasons.
Explain the term Emigration.
Give the different steps involved in the formation of mRNA from hnRNA.
In an ecosystem if the Net Primary Productivity (NPP) of first trophic level is 100x (kcal m-2)yr-1, what would be the GPP (Gross Primary Productivity) of the third trophic level of the same ecosystem?

A population of snakes lived in a desert with brown sand. Study the drawings given below showing the change in the population from ‘one’ to ‘two’ over time and answer the question that follows. Brown snakes and Grey snakes are represented by alleles A/a (Dominant/recessive). 

(a) If the frequency of the recessive trait is 9% in population-one, work out the frequency of homozygous dominant and heterozygous dominant snakes.
 

(iii) How do sense and anti-sense RNAs function?
Describe the nervous system in Planaria with a well-labeled diagram.