How to Answer Biology Exam Questions Properly

1. Arrange the columns appropriately and select the correct answer from the options given. Scientists Contributions related to the evolution of life (1) Thomas Malthus (P) Inheritance of Acquired Characters (2) Charles Darwin (Q) Population growth causes natural resources to become limited. (3) Jean Baptiste Lamarck (R) On the Origin of Species i. 1-P, 2-R, 3-Q ii. 1-R, 2-Q, 3-P iii. 1-Q, 2-P, 3-R iv. 1-Q, 2-R, 3 - P Answer To solve this question, match each scientist with their correct contribution to the theory of evolution. (1) Thomas Malthus is known for the idea that population growth tends to outstrip resources, leading to competition. Matches with (Q) (2) Charles Darwin is known for the theory of natural selection. Authored On the Origin of Species.Matches with (R) (3) Jean Baptiste Lamarck proposed the theory of Inheritance of Acquired Characters (e.g., giraffe's neck elongation due to stretching).Matches with (P) Answer is iv. 1 - Q, 2 - R, 3-P 2. Evaluate the statement and reason. Then choose the correct answer. Statement: The roan coat seen in some cattle and horses is an example of co- dominance. Reason: The allele for the dominant trait cannot completely mask the allele for the recessive trait. i) The statement and reason are correct. ii) The statement is false, but the reason is correct. iii) The statement is true, but the reason is incorrect. iv) Both the statement and reason are incorrect. To reach the correct answer, we need to analyse the Statement and the Reason separately, and then see whether the Reason correctly explains the Statement. Step 1: Understand the Statement Statement: The roan coat seen in some cattle and horses is an example of co-dominance. What is co-dominance? In co- dominance, both alleles are equally expressed in the heterozygous condition. Roan coat: It appears when red (RR) and white (WW) coat colour alleles are both expressed together. This leads to a coat with both red and white hairs visible. So, this is a correct example of co-dominance. The Statement is TRUE. Step 2: Understand the Reason Reason: The allele for the dominant trait cannot completely mask the allele for the recessive trait. This is a description of incomplete dominance, not co- dominance. In co-dominance, both alleles are dominant and equally expressed. In incomplete dominance, the dominant allele partially masks the recessive one, leading to a blend. So, the Reason is INCORRECT for explaining co-dominance. Step 3: Choose the correct option. Option iil) The statement is true, but the reason is incorrect. 3. Observe the figure and answer the questions given below. (a) Identify the figure. (b) What is the Importance of this picture? Answer (a) Photo 51 (b) Jarnes Watson, along with Francis Crick, presented the double helical model of DNA. Their discovery was based on the X-ray diffraction studies done by Rosalind Franklin and Maurice Wilkins. Watson and Crick got crucial information from the famous 'Photo 51'. It was an X-ray diffraction image of DNA taken by Rosalind Franklin. To find the right answer, first look carefully at Photo 51. Then, connect it to your knowledge of the discovery of DNA structure. 4 .An idea from a theory related to evolution is given below. The giraffe's neck elongates as it stretches to reach leaves on tall branches when food is scarce. (a) Which theory is this? (b) What evolutionary idea was put forward by this theory? (b) What evolutionary idea was put forward by this theory? (c) Why was this theory rejected by the scientific community? Answer (a) Lamarckism (Theory of inheritance of acquired characteristics) (b) Acquired characteristics are passed down through generations, leading to the emergence of giraffes with longer necks. (c) Later scientists proved that acquired variations do not cause changes in the genetic makeup of organisms. Therefore, they are not inherited. To answer this question, use what you know about evolutionary theories- especially Lamarck's theory and how it differs from modern genetics. Given idea: The giraffe's neck elongates as it stretches to reach leaves on tall branches when food is scarce. This statement suggests that a trait developed during an organism's lifetime (longer neck due to stretching) Is passed on to the next generation. This idea is a classic example of Lamarck's theory. And this theory is called Lamarckism or the Theory of Inheritance of Acquired Characteristics. 5 . Redraw the figure and identify and label the parts according to the statements given below. (a) The part that regulates the rate of ventilation. (b) The part that helps in maintaining homeostasis. (c) The part that helps to maintain the equilibrium of the body. To find the correct answer, you must know the different: parts of the brain and their functions. Identify the brain parts mentioned in the question based on their roles. Label them accurately on the diagram.