Q1. How are fossils helpful in developing evolutionary relationships
Q2.Wings of bird and wings of insect-are these organs homologous or analogous?
Q3. )Give one difference between eyes and eye spot.Which animal possesses eye spots?)What are various ways by which genes can enter a population?
Q4.Mention the ways by which variant genotypes are produced in organism?
Q5.What for did Mendel use the term factors and what are these factors called now. d. What are genes? Where are the genes located?
Q6.
Answers
Ans 4. a) Gene mutations. b) Crossing over. c) Hybridization
Ans 5. Genes are functional unit of DNA .
1. By providing links within two groups indicate that one species had evolved from the other species. For eg: a fossil called archaeopteryx show characteristics of both reptiles and birds.Teeth are like reptiles and wings like birds. Therefore, it show link between the birds and reptiles.
2. Wings of insect and bird are analogous because they have same function but different evolutionary origin.
3. Eyes are the well developed organ that help in formation of clear image whereas eye spots is rudimentary organ that help the animal to differentiate between darkness and day light. Eg: Euglena, Planaria possess eye spots.
Different ways through which genes can enter a population are:
i. Gene migration is a gene flow which occur when some member of one population migrate from one place to another.
ii. Gene drift is a change occur in gene frequency which cause due to accident or chance but does not occur due to natural selection.
iii. By the mecahnism of natural selection better genes are choose by the nature and allow to live and multiply.
iii. Mutations are the sudden changes in the gene inherited by off-springs.
4. The ways through which variant genotypes are produce in organisms are-
Gene mutation
Crossing over
Hybridization
5. For the units of inheritance of characters Mendel had use the term factors. These factors are said as genes.
Gene is a hereditary unit, present in segment of DNA which is situated on a chromosome at a particular position or locus.