What evidence do we have for the origin of life from inanimate matter?
Stanley L. Miller and Harold C. Urey provided evidence regarding origin of life from inanimate matter. They assembled an atmosphere similar to that existed on early earth. The atmosphere had molecules like ammonia, methane, hydrogen sulphide and water, but no oxygen. The mixture was maintained at a temperature just below 100â—¦C and sparks were passed through the mixture of gases. At the end of a week, 15% carbon from methane had been converted to simple compounds of carbon like aminoacids which make up protein molecules. So, life arose afresh on earth.
Define variation in relation to a species. Why is variation beneficial to the species? [Delhi]
How are fossils formed? Describe, in brief, two methods of determining the age of fossils. [All India]
a) Name the scientist who gave the theory of origin of life on earth. What is this theory ?
(b) How are those species which are now ‘extinct’ studied ?
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Why or why not ?
Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]
If the trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier ?
(a) What is the genotype of dwarf plants which always produced dwarf offspring ?
(b) What is the genotype of tall plants which always produced tall offspring ?
(c) What is the genotype of
(a) If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (;) sperm cell, and (ii) zygote ?
(b) What sizes of plants are produced if both parents have genes Tt ?
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement ? Why or why not ?
How is the equal genetic contribution of male and female parents ensured in the progeny? [Delhi]
Explain with examples how the following are evidences in favour of evolution in organisms. (i) Homologous organs (ii) Analogous organs (iii) Fossils [Delhi]
Name the first scientist who studied the inheritance of traits from one generation to the next.
(a) What will you get in the F1 and F2 generations in the following cross ?
Pure tall pea plant x Pure dwarf pea plant
(b) Is it an example of monohybrid cross or dihybrid cross ?
(a) Define ‘speciation’. Explain how speciation occurs.
(b) Will geographical isolation be a major factor in the speciation of a self-pollinating plant species ? Give reason for your answer.
What do you understand by the double helical structure of DNA? Who proposed this structure?
The human beings who look so different from each other in terms of colour, size and looks are said to belong to the same species. Why? Justify your answer. [All India(C)]
What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]
(a)What is meant by ‘heredity’ ? What are the units of heredity.
(b) State Mendel’s first law of inheritance.
(a) Why did Mendel choose pea plants for conducting his experiments on inheritance ?
(b) State Mendel’s second law of inheritance.
The forelimbs of a frog, a bird and a man show the same basic design (or basic structure) of bones. What name is given to such organs ?
Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) The human forelimb and bat’s forelimb are an example of……………………organs whereas an insect’s wing and a bat’s wing are an example of…………………organs.
(b) The evolution of eye is an example of evolution by…………………
(c) The scientific name of all human beings is……………………..
(d) Broccoli has evolved from……………..by the process of artificial selection.
(e) The theory of natural selection for evolution was proposed by………………………
Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.
The gene for red hair is recessive to the gene for black hair. What will be the hair colour of a person if he inherits a gene for red hair from his mother and a gene for black hair from his father ?
Gregor Mendel’s first law of genetics states “Of a pair of contrasted characters, only one can be represented in a gamete by its internal ‘factor’.
(a) Give the modern name for this ‘factor’.
(b) State where these factors are found in gametes.
Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive :
(a) Yellow seed (b) Round seed
Out of the wing of a bird, wing of an insect and the wing of a bat :
(a) which two are homologous organs ?
(b) which two are analogous organs ?
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics ?
Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.
