Matric Notes Biology Class 10th Ch 15 Inheritance Short Questions

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Q1: If a man with type AB blood group marries a woman with type O blood group. What type of blood group do you except in the offspring.

Ans: Blood group: Any of the various types of human blood whose antigens characteristic determine compatibility on transfusion.

Known blood group: The best known blood group are those of the ABO system.

Statement: A man with blood group- AB when marries with O blood group woman. Their offspring will be having the following possible blood groups.

• Their offspring will have A or B blood groups.

Q2: How can crossing bring variations?

Ans: Crossing over: Crossing over, or recombination, is the exchange of chromosome segments between non sister chromatids in meiosis. Crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity.

Variation in crossing over: Variation comes from crossing over, which may occur during prophase I of meiosis. In prophase I of meiosis, the replicated homologous pair of chromosomes comes together in the process called synapsis, and sections of the chromosomes are exchanged.

Q3: How are DNA and proteins packed to form a chromosome?

ANS: Chromosomes are composed of chromatin material.

In prokaryotes: In prokaryotes the chromatin material is composed of DNA only.

In eukaryotes: In eukaryotes, the chromatin material is composed of DNA and histones protein.

Process: Long molecules of DNA is wrapped around the bundle of histones. The structure made of histones and DNA wrapped around them, is called nucleosomes. Nucleosomes are arranged in the form of beads on string. This string of beads coil and forms the structure of chromosomes.

Q4: How is artificial selection used for the improvement of crops?

Ans: Artificial selection: When farmers and breeders allowed only the plants and animals with desirable characteristics to reproduce, causing the evolution of farm stock. This process is called artificial selection because people (instead of nature) select the organisms they want to reproduce.

Crop improvement: Essentially all present day crops have been extensively reshaped from their wild ancestors by the repeated applications of artificial selection. The major cereals (rice, wheat, maize, sorghum and millet) where all developed from wide greases by artificial selection between 7,000 and 12,000 years ago. Artificial selection has also been used to shape the aesthetic features of organisms that surround us everyday life. Many ornamental plants are the result of selection for attractive features.

Animal improvement: The diversity in domestic pets, such as breeds of dogs, cat, rabbits, or horses is to a large extent the result of selection of features that particular breeders regarded as desirable.

Q5: Differentiate between different types of dominant relations.

Ans: Dominance relation:

1. One of the Gregor, Mendel’s greatest contribution to the study of hereditary was the concept of dominance.
2. According to the Mendel conclusion, some traits were completely dominant over the other.
3. The dominance relation is the following types.

i. Complete dominance
ii. Incomplete dominance
iii. Co-dominance

➢ Complete dominance: When one allele of a character is completely dominant over the other allele and completely masks the recessive allele , this relation is known as complete dominance.

Example:

The allele of tallness (T) is completely dominant over dwarf (t).
The allele of round seed(R) is completely dominant over wrinkle (r).

Explanation:

1. When tall pea plant is cross fertilized with dwarf pea plant, then all plants of F1 generation appeared tall.
2. In the heterozygous condition ‘Tt’ the dwarf character is completely masked.
3. When plants of F1 generation were allowed to self- fertilized the tall to dwarf ratio in F2 generation was 3:1.

➢ Incomplete dominance: When a given allele does not completely mask the action of a second allele, rather they interact in such a way that heterozygote phenotype is a blending/mixing of both is known as incomplete dominance.

Example: In the plant mirabilis jalapa, commonly called as four o’clock plant, the inheritance of flower colour is an example of incomplete dominance.

Explanation:

1. This plant produces two types of flowers red coloured (AA) and white coloured (aa).
2. Whenever a red flowered variety is crossed with white flowered variety, the hybrid (F1) is pink (Aa) intermediate between the two parents.
3. Thus the homozygote are either red or white but heterozygous are pink.
4. When cross image between pink, flowers in F2 generation one fourth is red flowered, one fourth white and half pink.
5. This cross is proved in the following checker board.

➢ Co-dominance: It is not an intermediate quantitative expression like incomplete dominance but in this case different alleles of a gene that are both expressed in a heterozygote condition are called co-dominance.

Example: Carl land Steiner discovered ABO blood group system in 1901.

Explanation:

1. ABO system has four different phenotypes, which are distinct due to a specific antigen on the surface of RBC.
2. Hereditary of blood groups is based on various combination of three alleles of one gene symbolized as Ia, Ib and I.
3. Sin genotypes are possible.
4. Both the IA and the IB, alleles are dominant to the allele. Thus IA IB

Q6: Write down the phenotypes of the individuals in the following table.

Ans:

Genotype	Phenotype
IA IA	Blood group A
IB IB	Blood group B
IB i	Blood group B
IA i	Blood group A
ii	Blood group O
IA IB	Blood group AB