Define a gene.
A gene is a small portion of the DNA, with codes for a particular polypeptide or a protein. In other words, it is the functional unit of the DNA. It is also responsible for the transmission of hereditary characters from the parents to the offspring.
What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]
Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.
What are the different ways in which individuals with a particular trait may increase in a population ?
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
Name five varieties of vegetables which have been produced from ‘wild cabbage’ by the process of artificial selection.
In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.
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
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Give reason for your answer.
Does geographical isolation of individual of a species lead to formation of a new species? Provide a suitable explanation.
Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]
State one characteristic which shows that the birds are very closely related to dinosaurs.
Write the names of at least three inorganic molecules which helped in the origin of life on the earth.
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 ?
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ why or why not ?
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
Explain the mechanism of sex determination in humans. [All India]
Or
With the help of a flow chart explain in brief how the sex of a newborn is genetically determined in human beings. Which of the two parents, the mother or the father, is responsible for determination of sex of a child? [Foreign]
What type of plants were used by Mendel for conducting his experiments on inheritance ?
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.
(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
An individual cannot pass on to its progeny the experiences of its lifetime.” Justify the statement with the help of an example and also give reason for the same. [Foreign]
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 ?
Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria ? Explain your answer.
Can the wing of butterfly and the wing of a bat be considered homologous organs ? Why or why not ?
During which stage can the chromosomes be seen clearly? Write the features of the eukaryotic and prokaryotic chromosomes.
State the meaning of inherited traits and acquired traits. Which of the two is not passed on to the next generation? Explain with the help of an example.
Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors ?