List of practice Questions

A student performed some crosses in plants and represented the result in the form of bar graphs as shown below. Each graph displays the phenotypic proportion of the progeny. Study the graphs and answer the questions: 

How does the disease spread?
Mention the source and the role of the following in providing defence against infection in the human body: (I) Histamine (II) Interferons
Work out separate monohybrid crosses up to F2 generation between two pea plants and two Antirrhinum plants, both having contrasting traits with respect to the colour of the flower. Comment on the patterns of inheritance in the crosses carried out in such two cases.
How does a chromosomal disorder differ from a Mendelian disorder? Write one example for each.
Name the phenomenon that leads to situations like ‘XO’ abnormality in humans. Also name this genetic disorder. How are individuals with an XO chromosomal abnormality affected? Write its symptoms as well as karyotype.
Draw the structure of an antibody molecule and label any four of its parts.
Differentiate between active and passive immunity. Write any three differences.
Write the scientific names of the two species of filarial worms causing filariasis.
How do they affect the body of infected persons?
Briefly explain the events of fertilisation and implantation in an adult human female.
Arrange the following hormones in sequence of their secretion in a pregnant woman: hCG; LH; FSH; Relaxin.
Mention the source and the functions of the above mentioned hormones.
Explain the level of biodiversity at genetic, species, and ecological levels with the help of one example each.
Study the given chart showing the evolution of plants. Answer the following questions:
(a) Identify the plant which acts as an immediate ancestor of both ferns and conifers.
(b) Name the nearest ancestors of flowering plants.
(c) Name the most primitive group of plants.
(d) Psilophytan provides common ancestry to which classes?
(e) Name the common ancestor of psilophytan and seed ferns.
(f) Name the common ancestor of mosses and tracheophytes.
Mention a product of human welfare obtained with the help of each of the following: (a) Saccharomyces cerevisiae
(b) Propionibacterium shermanni
(c) Aspergillus niger
(d) Trichoderma polysporum
(e) Acetobacter aceti
(f) Streptococcus
Transgenic animals are produced by man. Explain any three ways in which such animals can be beneficial to humans.
Explain Gause's 'Competitive Exclusion Principle' with the help of a suitable example.
Name the lymphoid organ that acts as a large reservoir of erythrocytes. Explain its role as a lymphoid organ.
Suggest how a virus-free healthy plant can be obtained from a diseased sugarcane plant.
In order to force bacteria to take up the recombinant DNA, they must be made competent. Explain how it can be achieved.
Differentiate between grazing food chain and detritus food chain.
Ecological pyramids are widely accepted but they still have some limitations. Write any two limitations.
List any three outbreeding devices that flowering plants have developed for cross-pollination and explain how they help to encourage cross-pollination.
Draw a labelled diagram of a 'replicating fork' showing the polarity. Why does DNA replication occur within such 'fork'?