(a) State one advantage of variation to a species.
(b) What are sex chromosomes ? How many sex chromosomes are there ? Name them.
a) The advantage of variation to a species is that it increases the chances of its survival in a changing environment.
(b) The chromosomes which determine the sex of a person are called sex chromosomes. There are two types of sex chromosomes ? X and Y chromosomes.
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
State one characteristic which shows that the birds are very closely related to dinosaurs.
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.
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 ?
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]
Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement. [Delhi]
Study the following cross and showing self-pollination in Flf fill in the blank and answer the question that follows
Write the names of at least three inorganic molecules which helped in the origin of life on the earth.
Does geographical isolation of individuals of a species lead to the formation of a new species ? Provide a suitable explanation for your answer.
What are homologous organs? Can the wing of a butterfly and the wing of a bat be regarded as homologous? Why? [All India]
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.
Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.
In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.
Does geographical isolation of individual of a species lead to formation of a new species? Provide a suitable explanation.
A man having blood group O marries a woman having blood group B and they have a daughter. What will be the blood group of the daughter ?
What are fossils ? Giving one example, explain how fossils provide evidence for evolution.
Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.
Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.
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?
Define variation in relation to a species. Why is variation beneficial to the species? [Delhi]