Define homologous organs.
Homologous organs are those organs, which have similar origin and basic plan of development, but may or may not differ in their functions. The forelimbs of a human, a bird and a horse are homologous organs.
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually ? Give reason for your answer.
What is meant by the term speciation? List four factors which could lead to speciation. [Delhi]
What are the different ways in which individuals with a particular trait may increase in a population ?
”The sex of the children is determined by what they inherit from their father and not their mother.” Justify.
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.
State one characteristic which shows that the birds are very closely related to dinosaurs.
Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.
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 ?
What type of plants were used by Mendel for conducting his experiments on inheritance ?
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 ?
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
Study the following cross and showing self-pollination in Flf fill in the blank and answer the question that follows
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 ?
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]
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]
(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
(a) What do you understand by the term ‘variation’ ?
(b) Name two human traits which show variation.
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.
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.
The human beings who look so different from each other in terms of colour, size and looks are said to belong to the same species. Why? Justify your answer. [All India(C)]
Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement. [Delhi]