What is a sex chromosome?
Sex chromosome is a chromosome that operates in the sex-determining mechanism of a species. Many animals have two different types of sex chromosomes. For example, in human there is a large X chromosome and a much smaller Y chromosome.
What are the different ways in which individuals with a particular trait may increase in a population ?
What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]
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.
State one characteristic which shows that the birds are very closely related to dinosaurs.
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
What type of plants were used by Mendel for conducting his experiments on inheritance ?
In human beings, the statistical probability of getting either a male or female child is 50 : 50. Give a suitable explanation.
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]
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.
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 ?
Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it. [All India]
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]
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 ?
Study the following cross and showing self-pollination in Flf fill in the blank and answer the question that follows
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement. [Delhi]
Can the wing of butterfly and the wing of a bat be considered homologous organs ? Why or why not ?
Write the names of at least three inorganic molecules which helped in the origin of life on the earth.
Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms ? Give reason for your answer.
(a) Define ‘natural selection’.
(b) “Only variations that confer an advantage to an individual organism will survive in a population”. Do you agree with this statement ? Give reason for your answer.
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ why or why not ?
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 ?
(a) What is meant by a species ? Give two examples of plant species and two of animals.
(b) State the various factors which could lead to the formation of new species.
Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.
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 ?