The Class 10 is an important year in a student’s life and Maharashtra State Board Science 2 is one of the subjects that require dedication, hard work, and practice. It’s a subject where you can score well if you are well-versed with the concepts, remember the important formulas and solving methods, and have done an ample amount of practice. Worry not! Home Revise is here to make your Class 10 journey even easier. It’s essential for students to have the right study material and notes to prepare for their board examinations, and through Home Revise, you can cover all the fundamental topics in the subject and the complete Maharashtra State Board Class 10 Science 2 Book syllabus.
1. Write short notes on Lamarckism.
Answer: Jean-Baptiste Lamarck, the French naturalist proposed that evolution is the result of the activities of the organisms. He stated that every animal or plant undergoes some changes in its lifespan and these changes are transferred to the next generation and such changes occur in subsequent generations too. Lamarck proposed that morphological changes that take place in living organisms result in evolution and the cause of these morphological changes is activities or laziness of that organism. He called this concept the principle of ‘use or disuse of organs’. It is seen that living organisms have the ability to transfer the characters that are acquired to the next generation and this is known as the ancestry of acquired characters. Take the example of the neck of the giraffe It is believed that it became too long as a result of the giraffes extending their neck for several generations to browse on leaves. This is an example of ‘acquired characters’ that are transferred from one to another generation. This is also known as the theory of inheritance of acquired characters or Lamarckism. However, while development of organs due to specific activities or their degeneration due to no use at all was widely accepted, the transfer of those characters from generation to generation. For the reason that it was verified many times, the changes brought in us are not transferred to the next generation and so this disproved Lamarck’s theory.
2. Define heredity.
Answer: Heredity is the transfer of biological characters from one generation to another via genes. This transfer of physical traits or mental characteristics occur via sexual or asexual production. It was proved that genes are carried via chromosomes and that except viruses, all living organisms use DNA as their genetic material.
3. Explain Speciation.
Answer: New species of plants and animals are created as an effect of evolution. Species, in the meantime, is the group of organisms that produce fertile individuals using natural reproduction. Each species develop within specific geographical conditions and has different food, habitat, reproductive ability and period. However, genetic variation results in creating new species from an earlier one. Apart from this, the geographical and reproductive changes are also responsible. Additionally, geographical or reproductive isolation also leads to speciation.
4. What is the first record of a human-like animal?
Answer: ‘Ramapithecus’ ape from East Africa is the first record of a human-like animal. Later, this ape grew in size and became more intelligent and thus the ape of South Africa is said to have evolved about 40 lakh years ago.
5. Darwin’s theory of natural selection was widely accepted for a long duration. However, what were some objections raised against the theory?
Answer: Some main objections to the Darwin’s theory are-
1. Natural selection is not the only factor that is responsible for evolution
2. Darwin did not give any explanation about useful and useless modifications.
3. There is no explanation about slow changes and abrupt changes.
6. What is “Carbon dating?”
Answer: Carbon consumption of animals and plants ceases after death and only the decaying process of C-14 occurs continuously after that. Meanwhile, inside dead bodies of plants and animals, the ratio between C-14 and C-12 modifies continuously instead of remaining constant because C-12 is non-radioactive. Hence, it is possible to calculate the time passed since the death of a plant or animal by measuring the radioactivity of C-14 and ratio of C-14 to C-12 present in their body. This method is known as the ‘carbon dating’ method was applied in palaeontology and anthropology for determining the age of human fossils and manuscripts. On identifying the age of fossils with such technique, it becomes easy to determine the information about other erstwhile organisms. The carbon dating method is according to the radioactive decay of naturally occurring C-14 and it is developed by Willard Libby.
7. What is connecting links? How is it possible to indicate that Peripatus is the connecting link between annelida and arthropoda?
Answer: In some plants and animals, some morphological characters are evident by which they can be related to two different groups, and so they came to be called ‘connecting links’. Example: Peripatus have characters like, segmented body, thin cuticle, and parapodia-like organs are present. These animals also show tracheal respiration and an open circulatory system similar to arthropods, thus indicating that Peripatus is the connecting link between annelida and arthropoda.
8. How did gibbon and orangutans evolve?
Answer : Approximately, around the time that last dinosaurs disappeared, monkey-like animals are said to have evolved from some ancestors who were more or less similar to the modern lemurs. Around some 4 crore years ago, the tail of these monkey-like animals of Africa is said to have disappeared. They developed due to enlargement in the brain and their hands also improved, thus evolving ape-like animals. Meanwhile, these ape-like animals reached the South and North-East Asia and at last evolved into gibbon and orangutan.