How do Mendel’s experiments show that traits are inherited independently ?
In a dihybrid cross made by Mendel, it was observed that when two pairs of traits or characters were considered; each trait expressed independent of the other. Thus, Mendel was able to propose the Law of Independent Assortment which says about independent inheritance of traits.
(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]
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 ?
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]
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.
Does genetic combination of mother play a significant role in determining the sex of a new born baby ?
(a) What do you understand by the term ‘variation’ ?
(b) Name two human traits which show variation.
State one characteristic which shows that the birds are very closely related to dinosaurs.
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 ?
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
Give an example of characteristics being used to determine how close two species am in evolutionary terms ?
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ 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?
Describe briefly four ways in which individuals with a particular trait may increase in a population. [Foreign]
How is the equal genetic contribution of male and female parents ensured in the progeny? [Delhi]
Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]
What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]
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 ?
(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) 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
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
(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.
