1. Heredity and Evolution
Q.1. complete the statements by choosing the correct options from bracket.
1. the causality behind the sudden changes was understood due to mutation principle of Hugo de Vries.
2.the proof for the fact that protein synthesis occurs through gene was given by George beadle and Edward Tatum.
3.transfer of information from molecule of DNA to mRNA is called as transcription process.
4.evolution means gradual development.
5.vestigial organ appendix present in human body is proof of evolution.
Q.2 ANSWER THE FOLLOWING
1 .evolution means gradual development.
5.vestigial organ appendix present in human body is proof of evolution.
Q.2 ANSWER THE FOLLOWING
1. Define heredity. explain the mechanism of hereditary changes.
ANS; i. Heredity is defined as the transfer of biological characters from one generation to another via genes.
ii. The mechanism of hereditary changes is as follows;
a.Diversity or hereditary changes occur due to genetic variation.
b.In sexually reproducing organism, fusion of gametes from male and female parents occurs, the offspring always has recombined genes of both parents.
c. Also, sometimes sudden changes known as mutation occur in the genes. A change in the position of even a single nucleotide can cause either a minor effect or a considerable alteration in the characters of an individual.
d.If there are changes (mutation) occur in DNA of germ line cells then, these changes would be inherited to the next generation.
2.how are the hereditary changes responsible for evolution?
ANS: i. Evolution is the gradual change occurring in living organisms over a long duration.
ii. Certain heritable sudden changes may occur in thye genes of an individual resulting in genetic variations.
iii. These genetic variations are responsible for the formation of news species for the formation of new species from the earlier ones.
iv. According to darwin's theory, organisms with favorable or beneficial are selected by nature whereas the others with non-favorable variations.
v. This leads to formation of new species due to species changes in species characters accumulated through several generations in sustained and selected organisms.
3.Write a short note on evolution.
ANS:1.Evolution is defined as the gradual change occurring in living organisms over a long duration.
2.It is a slow-going process through which development of organisms is achieved.
3.Evolution is thus the formation of new species due to changes in species characters of living organisms.
4.Changes in these specific characters get accumulated over several generations of living organisms in response to natural selection.
4.Explain the process of formation of complex proteins.
ANS:1. Around 3.5 billion years ago, it is speculated that life was non-existent on earth.
2. In the beginning, only simple elements may have been present in the oceans.
3. Simple organic and inorganic compounds may have been formed by these simple elements.
4.these simple compounds may have eventually resulted in the formation of complex compounds like proteins and nucleic acids.
5.the process of formation of complex proteins from simple elements may have occurred over a long period of several years.
5. Explain with suitable examples importance of anatomical evidences in evolution.
ANS: 1. the hand of human; foreleg of cat, flipper of bat appear different superficially or morphologically.
2. Also, the function of these structures is different in different animals.
3. However, there is a similarity in the structure of bones and bony joints in the organs these animals.
4.these similarities indicate that the animals evolved from a common ancestor.
6.Write a short note on connecting link.
ANS:1. connecting link are some plants or animals that show morphological characters by which they can be related to two different groups of organisms.
2. the duck-billed platypus is a connecting link between mammals and reptiles. it shows similarity with mammals due to the presence of mammary glands and hairs. it lays eggs like reptiles.
3.lungfishes are connecting links between fishes and amphibians. the lungfish performs respiration with lungs even though it is a fish.
7.Write a short note on embryology.
ANS: 1. embryology is a branch of biology that deals with the study of different stages of development of embryo.
2. as the development embryo grows, in the first few weeks, there is increase in complexity from differentiation of the cells into specialized tissues to from specific organs.
3. embryology enables us to comparatively study the development stage of various animals.
8.write a short note on darwin's theory of natural selection.
ANS: Darwins theory of natural selection is based on the concept of survival of the fittest.
2.the organisms can reproduce prolifically.
3. according to this theory, only those organisms survive which show modifications for winning the competition. this gives rise to new species with their specific set of characters
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