1. Species maintain continuity by reproduction.
2. Variation in different degrees occur.
3. Variants have unequal chances of survival.
4. In sexually reproducing individuals, for the same trait genes have two copies. Unidentical
copies bear dominant and recessive nature.
5. Traits separately inherited, yields new combinations of traits in progeny.
6. The sex of human progeny is determined by the sex chromosomes inherited from father.
7. Variation in combination with geographical isolation might lead to speciation.
8. Evolutionary relationship among living organisms become visible in hierarchy of classification.
9. Study of living forms as well as dead remains of organisms emerges as evolutionary scene.
10. DNA changes accumulated over a time span has resulted in evolution of complex organs like eye as exhibited by structure of eye in different animals.
11. Features like feathers have evolved as a function of change in allocated task.
12. Evolution is not progress from lower to higher forms.
1 mark questions :-
1. Which of the two exhibit greater variation : asexual or sexual reproduction?
2. Why all the variants don't have equal chances of surviving?
3. What is heredity?
4. At which place on earth did humans appeared first?
5. Give the name of plant studied by Mendel?
6. Name the acid which is information source for making proteins in cells.
7. What is the chemical nature of enzymes?
8. Define gene.9. Which one of the two is shorter in length 'X' or 'Y'?
Chapter - 9 Heredity and Evolution read more............
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