What factors could lead to the rise of a new species ?
Genetic variations, natural selection and reproductive isolation could lead to the rise of a new species.
(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 ?
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Why or why not ?
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 ?
How are fossils formed? Describe, in brief, two methods of determining the age of fossils. [All India]
State one characteristic which shows that the birds are very closely related to dinosaurs.
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
A man with blood group A marries a woman with blood O and their daughter has blood group O. Is this information enough to tell you which of the traits blood group A or O is dominant ? Why or why not ?
Give an example of characteristics being used to determine how close two species am in evolutionary terms ?
Who provided the evidence of DNA as the genetic material? Write the names of the components of the DNA molecule.
Define variation in relation to a species. Why is variation beneficial to the species? [Delhi]
How is the equal genetic contribution of male and female parents ensured in the progeny? [Delhi]
State whether the following statement is true or false :
The sex of an infant is not a case of inheritance of characteristics.
Name the first scientist who studied the inheritance of traits from one generation to the next.
Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) Genes always work in …………………
(b) In pea plants, the gene for dwarfness is………………… whereas that for tallness is…………………
(c) Most people have………………… earlobes but some have………………… earlobes.
(d) A human gamete contains………………… chromosomes whereas a normal body cell has………………… chromosomes in it.
(e) All races of man have………………… blood groups.
(f) The………………… chromosomes for a………………… are XX whereas that for a………………… are XY.
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.
Does genetic combination of mother play a significant role in determining the sex of a new born baby ?
(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.
(a) What do you understand by the term ‘variation’ ?
(b) Name two human traits which show variation.
Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species ?
Name five varieties of vegetables which have been produced from ‘wild cabbage’ by the process of artificial selection.
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Give reason for your answer.
Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.
(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.
Does the occurrence of diversity of animals on earth suggest their diverse ancestry also? Discuss this point in the light of evolution.
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics ?
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ why or why not ?
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 ?
During which stage can the chromosomes be seen clearly? Write the features of the eukaryotic and prokaryotic chromosomes.
What do you understand by the double helical structure of DNA? Who proposed this structure?
