CBSE Class 10 Science Biology Heredity and Evolution Assignment

Question : Name the organ analogous to the wings of birds. 
a. Forelimb of human
b. None of these
c. wings of insect
d. Fore-leg of horse

Answer : C
Explanation: Wings of bird and wings of insect both are analogous as both of them perform the same function of flight while structures and origin are different. Feathers of birds originate from their forelimbs, the wings of insects originate from the inner or outer surface of the insect’s body.
Question : Which of the following is not correct-
a. For every molecule of fat there is a gene
b. For production of every enzyme there is a gene
c. For every protein there is a gene
d. For every hormone there is a gene

Answer : A
Explanation: Hormone and enzymes are proteins and formation of any particular protein is controlled by a particular gene. Hence, all other options are correct.
Question : What are the carriers of factor? 
a. Chromosomes
b. Genes
c. Alleles
d. DNA

Answer : A 
Explanation: The carriers of factor (genes) are chromosomes and transfer hereditary information from one generation to another. 
Question : Human being belongs to the species of 
a. Homo habillis
b. Hominidae
c. Homo sapiens
d. Homo erectus

Answer : C 
Explanation: The billions of human beings living today all belong to one species: Homo sapiens. As in all species, there is variation among individual human beings, from size and shape to skin tone and eye color. But we are much more alike than we are different. 
Question : Haemophilia is more commonly seen in human males than in human females because 
a. This disease is due to an X-linked recessive mutation
b. A greater proportion of girls die in infancy
c. This disease is due to an X-linked dominant
d. This disease is due to a Y-linked recessive mutation

Answer : A
Explanation: Hemophilia is a bleeding disorder that slows down the blood clotting process. People who have hemophilia often have longer bleeding after an injury or surgery.
Hemophilia is inherited in an X-linked recessive pattern. A condition is considered X-linked when gene mutation that causes it is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is enough to cause the condition. Since females have two X chromosomes, a mutation must be present in both copies of the gene to cause the hemophilia. Males are affected by Xlinked recessive disorders much more frequently than females. 

Question. Recessive mutations are expressed
(a) always since it is a mutation
(b) in heterozygous condition
(c) neither in homozygous nor in heterozygous condition
(d) in homozygous condition.

Answer : D

Question. XX-XO type of sex determination and XX-XY type of sex determination are the examples of 
(a) male heterogamety
(b) female heterogamety
(c) male homogamety
(d) both (b) and (c).

Answer : A

Question. A plant bearing purple flowers (RR) was cross pollinated with a plant bearing white flowers (rr). What would be the ratio of the plants bearing white flowers and purple flowers respectively in F2 generation when the F1 progeny were self pollinated? 
(a) 1 : 3
(b) 3 : 1
(c) 1 : 1
(d) 2 : 1

Answer : A

Question. In a dihybrid cross four phenotypes form in the ratio of 9 : 3 : 3 : 1, because of 
(a) dominance of one phenotype in each pair ofcontrasting traits
(b) independent assortment of the genes of contrasting traits
(c) crossing over of genes
(d) mixed effect of dominance and independent assortment.

Answer : B

Question. Some of the dominant traits studied by Mendel were 
(a) round seed shape, green seed colour and axial flower position
(b) terminal flower position, green pod colour and inflated pod shape
(c) violet flower colour, green pod colour and round seed shape
(d) wrinkled seed shape, yellow pod colour and axial flower position.

Answer : C

Question. Why were pea plants more suitable than dogs for Mendel’s experiments ? 
(a) There were no pedigree records of dogs.
(b) Pea plants can be self-fertilised.
(c) All pea plants have only two chromosomes.
(d) Dogs have many genetic traits.

Answer : B

Question. Select the incorrect statement. 
(a) In male grasshoppers, 50% of sperms have no sex chromosome.
(b) Female fruitfly is heterogametic.
(c) Human male produces two types of sperms 50% having X chromosome and 50% having Y chromosomes.
(d) In turtle, sex determination is regulated by environmental factors.

Answer : B

Question. Mendel conducted his famous breeding experiments by working on 
(a) Drosophila
(b) Pisum sativum
(c) Escherichia coli
(d) all of these.

Answer : B

Question. The genotypic ratio in F2 generation of monohybrid cross will be 
(a) 1 : 2 : 1
(b) 3 : 1
(c) 1 : 1
(d) 1 : 2.

Answer : A

Question. The main reason for Mendel’s success in discovering the principles of inheritance was 
(a) he considered each character separately
(b) he was lucky not to encounter with linkage problem
(c) the plant was pure breeding
(d) all of these.

Answer : D

Assertion & Reasoning Based MCQs

(a) Both assertion and reason are true, and reason is correct explanation of the assertion.
(b) Both assertion and reason are true, but reason is not the correct explanation of the assertion.
(c) Assertion is true, but reason is false.
(d) Assertion is false, but reason is true.

Question. Assertion : Test cross is a back cross. 
Reason : In test cross, individual is crossed with recessive parent.

Answer : B

Question. Assertion : The principle of segregation given by Mendel is the principle of purity of gametes. 
Reason : Gametes are pure for a character and do not mix up.

Answer : A

Question. Assertion : In grasshoppers, females are heterogametic and males are homogametic. 
Reason : In grasshoppers, male has only one sex chromosome (XO) whereas the female has sex chromosomes (XX).

Answer : D

Question. Assertion : Pure lines are called true breeds. 
Reason : True breeds are used for cross breeding.

Answer : B

Question. Assertion : If mother is homozygous for black hair and father has red hair then their child can inherit black hair. 
Reason : Gene for black hair is recessive to gene for red hair in humans.

Answer : C

Question. Assertion : A child which has inherited X chromosome from father will develop into a girl child. 
Reason : Girl child inherits X chromosome from father and Y chromosome from mother.

Answer : C

Question. Assertion : In a monohybrid cross, offspring of F1 generation express dominant character. 
Reason : Dominance occurs only in heterozygous state.

Answer : C

Question. Assertion: The traits that are obtained from parents are inherited traits. 
Reason : These traits were developed in the parents during their lifetime.

Answer : C

Question. Assertion : If blood group of both mother and father is ‘O’ then the blood group of children will also be O. 
Reason : Blood group in humans is determined by many alleles of a gene viz. IA, IB, IO.

Answer : B

Question. Assertion : Mendel successfully postulated laws of heredity. 
Reason : He recorded and analysed results of breeding experiments quantitatively.

Answer : A


Very Short Answers


Question : What is gene? Where are genes located? 
Answer :  Gene is a segment of DNA on chromosomes occupying specific position. Genes are located on chromosomes.
Question :  Where will you find the most ancient and recent fossil? 
Answer : The most ancient fossils will occur in the older rocks: whereas most recent fossils willoccur in the youngest rocks.
Question : Name the Father of Genetics. 
Answer : Gregor Johann Mendel  
Question :  How many contrasting traits Mendel noted in garden pea? 
Answer : Seven 

Short Answers

Question : What is natural selection in modern terms? Elucidate the three different effects of natural selection on variation. 
Answer :  Natural selection: In modern term natural selection is differential reproduction.
Natural selection is main evolutionary process which causes the change of allele frequencies or in other words selection is the consistent differences in contribution of various genotypes to the next generation.
If in a population both small and largest individuals contribute relatively fewer offspring to the next generation then those closer to the average size do, stabilizing selection is operating.
If centre of population contributes more then equilibrium is maintained while if extremes of population work then two peaks in the distribution of a trait produced, while former is disruptive selection.

Question : What is speciation? List four factors that could lead to speciation. Which of these cannot be a major factor in the speciation of a self-pollinating plant species? Give reason to justify your answer. 
Answer :  Speciation is the process by which new species develop from the existing species.
Factors responsible for speciation are as follows
i. Genetic drift
ii. Mutation
iii. Natural selection
iv. Migration
Out of the following, geographical isolation will not be a major factor in the speciation of a self-pollinating plant species. Because, here single parent is involved as male and female gametes both are contributed by same individual. Hence, even though if a selfpollinating plant is seperated geographically they can reproduce without creating much variation. 
Question : In evolutionary terms can we say that which among bacteria, spider, fish and chimpanzee has a 'better' body design? Why or why not? 
Answer : It depends on our perception of ‘better’ design. If complexity of body design is the criterion, then chimpanzee is obviously better than bacteria. But if ability of survival in almost all kinds of habitat is a criterion then bacteria are far ahead than any other group of organisms.
Question : Give difference between diploid and haploid.
Answer : 

Long Answers

Question : Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Provide a suitable explanation.
Answer :  It depends on our perspective through which we try to evaluate evolution. If complexity in body design is the parameter to define evolution, then human beings are more evolved than bacteria. Human beings are multicellular with organ system level of organisation whereas bacteria is unicellular and show cellular level of organization. In terms of complexity human beings are definitely highly evolved compared to bacteria.
But when we compare the ability of survival, then situation is just opposite. Human beings are living in almost every part of the earth, but they can live only on land Moreover, in extreme environmental conditions, human beings make artificial facilities to counter the adverse conditions. This means their body is not adapted to withstand extreme climatic conditions they have to thrive on artificially created resources. Bacteria, on the other hand, are known to be present almost everywhere on earth. They are known to live even in some of the harshest conditions; like Sulphur spring, crater of volcano, etc. Bacteria can survive in highly acidic environment and they can survive extreme temperatures. From this angle, bacteria can be considered as more evolved than human beings.

Question : Name any five vegetables generated from a common ancestor through artificial selection rather than natural selection. Also mention the features for which each vegetable is selected? 
Answer :  Humans have, for more than two thousand years, cultivated wild cabbage. They have selected various character artificially rather than selecting naturally, which led to development of various species. It has resulted in generation of the following vegetables due to some specific characters such as:
i. Cabbage selected for short distance between leaves.
ii. Broccoli selected for arrested flower development and thick stem.
iii. Cauliflower selected for sterile flowers forming a large flower.
iv. Kohlrabi selected for a swollen edible stem.
v. Kale selected for large leaves.


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