What are the chromosomes XY and XX known as ?
Sex Chromosomes.
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
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.
What type of plants were used by Mendel for conducting his experiments on inheritance ?
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]
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 individual of a species lead to formation of a new species? Provide a suitable explanation.
Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.
Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.
If a 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
What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]
If we cross pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F2 generation, then we obtain pea plants of F2 generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F2 generation but appeared in F2 generation, mentioning the reason for the same. [All India]
Name the first scientist who studied the inheritance of traits from one generation to the next.
(a) What do you understand by the term ‘variation’ ?
(b) Name two human traits which show variation.
Does geographical isolation of individuals of a species lead to the formation of a new species ? Provide a suitable explanation for your answer.
Who provided the evidence of DNA as the genetic material? Write the names of the components of the DNA molecule.
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.
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 ?
(a) What are genes ? Where are they located in our body ?(a) What are genes ? Where are they located in our body ?
(b) What is meant by dominant genes and recessive genes ? Give one example of each.
(c) Explain how, characteristics (or traits) are inherited through genes.
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………………………