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Concise Biology Part II - Selina Solution for Class 10 Biology Chapter 3 - Genetics - Some Basic Fundamentals

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Selina Textbook Solutions Chapter 3 - Genetics - Some Basic Fundamentals

Selina Textbook Solutions are a perfect way to ace your examination with high marks. These Textbook Solutions are extremely helpful for solving difficult questions in the ICSE Class 10 Biology exam. Our Selina Textbook Solutions are written by our subject experts. Find all the answers to the Selina textbook questions of Chapter 3 - Genetics - Some Basic Fundamentals.

All solutions Selina textbook questions of Chapter 3 - Genetics - Some Basic Fundamentals are created in accordance with the latest ICSE syllabus. These free Textbook Solutions for ICSE Class 10 Selina Concise Biology will give you a deeper insight on the fundamentals in this chapter and will help you to score more marks in the final examination. ICSE Class 10 students can refer to these solutions while doing their homework and while studying and revising for the Biology exam. 

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Concise Biology Part II - Selina Solution for Class 10 Biology Chapter 3 - Genetics - Some Basic Fundamentals Page/Excercise 1

Solution A.2

(a) all tall

Solution A.3

(c) independent assortment

Solution A.4

(c) Gs and gs 

Solution B.1

(a) - (iii) Study of laws of inheritance of characters

(b) - (v) Chromosomes other than the pair of sex chromosomes

(c) - (iv) A gene that can express when only in a similar pair

(d) - (ii) The alternative forms of a gene

(e) - (i) Chromosomes similar in size and shape

Solution B.2

Colour-blindness, Thalassaemia, Sickle cell anaemia and Haemophilia (Any two)

Solution B.3

Homozygous dominant - RR

Homozygous recessive - rr

Solution C.1




The observable characteristic which is genetically controlled is called phenotype.

The set of genes present in the cells of an organism is called its genotype.





Any heritable feature is called a character.

The alternative form of a character is called trait.


Monohybrid cross

Dihybrid cross

Phenotypic ratio - 3:1

Phenotypic ratio- 9:3:3:1

Solution C.2

The characteristics of a species such as physical appearance, body functions and behavior are not only the outcome of chromosome number, but these depend on the genotype of every organism. That means the set of genes present in the organisms may very and therefore lion, tiger and domestic cat have the same number of 38 chromosomes, their characteristics (like different appearances) are the result of the genes located on the chromosomes.

Solution C.3


Dominant trait

Recessive trait

Flower Colour



Seed Colour



Seed Shape



Pod Shape



Flower Position



(Any 3)

Solution C.4

Colour-blindness is caused due to recessive genes which occur on the X chromosome.

Males have only one X chromosome. If there is recessive gene present on X chromosome, then the male will suffer from colour-blindness.

Females have two X chromosomes. It is highly impossible that both the X chromosomes carry abnormal gene. Hence, if one gene is abnormal and since it is recessive, its expression will be masked by the normal gene present on the other X chromosome. Females are unlikely to suffer from colour-blindness.

Solution C.5

Phenotypic Ratio - 3 (Black Fur) :1 (Brown Fur)

Genotypic Ratio - 1(Homozygous Black Fur):2 (Heterozygous Black Fur): 1 (Homozygous Brown Fur)

Solution D.1

(a)  Heterozygous:  The condition in which a pair of homologous chromosomes carries dissimilar alleles for a particular character.

For example -

(i) A daughter (XXo) from a normal homozygous mother for colour vision (XX) and a colour blind father has one normal and one defective allele (XoY).

(ii) Certain tongue rollers are heterozygous with Rr genotype.


(b)  Homozygous:  The condition in which a pair of homologous chromosomes carries similar alleles for a particular character.

For example -

(i) A colorblind daughter (XoXo) will have both the X chromosomes with defective alleles.

(ii) A non-roller will have rr (homozygous) genotype.


(c)  Pedigree Chart:  A pedigree chart is a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next. In the pedigree chart, males are shown by squares and females by circles.

Solution D.2

Mendel's laws of inheritance are:

(i) Law of Dominance Out of a pair of contrasting characters present together, only one is able to express itself while the other remains suppressed. The one that expresses is the dominant character and the one that is unexpressed is the recessive one.

(ii) Law of Segregation : The two members of a pair of factors separate during the formation of gametes. The gametes combine together by random fusion at the time of zygote formation. This law is also known as 'law of purity of gametes'.

(iii) Law of Independent Assortment: When there are two pairs of contrasting characters, the distribution of the members of one pair into the gametes is independent of the distribution of the other pair.

Solution D.3

The sex of the child depends on the father. The egg contains only one X chromosome, but half of the sperms contain X-chromosome whereas the other half contains Y-chromosome. It is simply a matter of chance as to which category of sperm fuses with the ovum and this determines whether the child will be male or female.

If the egg fuses with X-bearing sperm, the resulting combination is XX and the resulting child is female.

If the egg fuses with Y-bearing sperm, the resulting combination is XY and the resulting child is male.

Solution E.1










Genotype - 1(Homozygous Black Fur) :2 (Heterozygous Black Fur):1 (Homozygous Brown Fur)

Phenotype - 3 (Black Fur) :1(Brown Fur)

Solution E.2

(a) Black

(b) No

Solution E.3




F2 generation -














Genotype - 1(Homozygous tall) :2 (Heterozygous tall):1 (Homozygous dwarf)

Phenotype - 3 (Tall) :1(Dwarf)





F2 generation -














Genotype - 1(Homozygous red) :2 (Heterozygous red):1 (Homozygous white)

Phenotype - 3 (Red) :1(White)

Solution E.4

(a) Father

(b) Two sons and three daughters

(c) The child 1 (daughter) is colour blind

(d) X chromosome

(e) Haemophilia

Solution A.1

a) 3 : 1

TopperLearning provides step-by-step solutions for each question in each chapter. Access Chapter 3 - Genetics - Some Basic Fundamentals  for ICSE Class 10 Biology free of cost. The solutions are provided by our subject matter experts. Refer to our solutions for the Selina Concise Biology textbook to revise the whole chapter and clear your fundamentals before the examination. By referring to the solutions for this chapter and the others, we hope that you are able to write your exams well.

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