AP 10th Class Biology 8th Lesson Questions and Answers Heredity

AP State Board new syllabus AP Board Solutions Class 10 Biology 8th Lesson Heredity Questions and Answers.

10th Class Biology 8th Lesson Heredity Questions and Answers

10th Class Biology 8th Lesson Questions and Answers (Exercise)

Question 1.
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic makeup of the tall parent can be depicted as –
a) TTWW
b) TTww
c) TtWW
d) TtWw
Answer:
c) TtWW

Question 2.
A study found that children with light-coloured eyes are likely to have parents with light – coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
Answer:

• The light colour eye trait is dominant, then only its possible to express in progeny. Even one parent does not have that character.
• If its receive trait, it only express in homozygous condition.

Question 3.
Outline a project which aims to find the dominant coat colour in dogs.
Answer:
Coat colour in dogs :

• In both homozygous and heterozygous conditions the dominant gene is expressed.
• So far 11 genes have been identified that determine the coat color of dogs.
• A cross can be performed to determine the dominant gene.

Cross :

• Consider two parents – one homozygous black (BB) and the other homozygous brown (bb).
• When crossed they produce offspring with genotype Bb
• The dominant trait can be determined by looking at the offspring.
• If the offspring is brown in colour then brown is the dominant trait and if it is black, then black is the dominant trait.

Question 4.
How is the equal genetic contribution of male and female parents ensured in the progeny ?
Answer:

• Both parents must be contributing equally to the DNA of the progeny during sexual reproduction.
• If both parents can help determine the trait in the progeny, both parents must be contributing a copy of the same gene.
• This means that each pea plant must have two sets of all genes, one inherited from each parent.
• Thus, each cell will have two copies of each chromosome, one each from the male and female parents.
• Every germ cell will take one chromosome from each pair and these may be of either maternal or paternal origin.
• When two germ cells combine, they will restore the normal number of chromosomes in the progeny.

10th Class NS 8th Lesson Questions and Answers (InText)

Page No. 90

Question 1.
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60%of the same population, which trait is likely to have arisen earlier?
Answer:
In the given question we will see that trait B will be seen earlier.

• This happens because, in the case of an asexually reproducing population, the organisms will be the exact copy of their parents.
• Now if there is a mutation just in the case of trait A as we see, it will take time to appear in the population.
• Trait B being the majority will appear first.

Question 2.
How does the creation of variations in a species promote survival ?
Answer:
Variation :

• Variation refers to the differences that arise between the individuals of a species or a group of organisms.
• Variations arise as a mutation in the gene that encodes a protein.
• Variations in the genome of the organism give rise to altered phenotypes such as differences in colour.

Variation promotes the survival of species in the following ways:

• Variation improves the survival rate of species as it helps the individual organisms adapt based on altering environmental conditions.
• Variants formed due to environmental concerns form the basis for evolution.

Page No. 98

Question 3.
How do Mendel’s experiments show that traits may be dominant or recessive ?
Answer:

• By the Mendel’s monohybrid experiment we can decide the trait may be dominant or recessive.
•  If both parents are homozygous, the traits which express in F1 generation is dominant. In this condition all F1 generation have same phenotype.
• If F1 generation has different phenotype we go to test cross to decide the dominant trait.
• A test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype.

Question 4.
How do Mendel’s experiments show that traits are inherited independently ?
Answer:
During dihybrid cross by Mendel, it was observed that when two pairs of traits were considered; each trait expressed independently of the other. Thus, Mendel was able to propose the Law of Independent Assortment which says about the independent inheritance of traits.

Question 5.
A man with blood group A marries a woman with blood group $O$ and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
Answer:

• No. This information is not sufficient to determine which of the traits – blood group A or O – is dominant.
• This is because we do not know about the blood group of all the progent. Blood group A can be genotypically AA of AO.
• In blood heredity, blood type A is always dominant and blood type O is always recessive.
• Here, father’s blood group can be AA (homozygous) or AO (heterozygous) genotypically, whereas that of the mother can be A O or OO.
• For daughter to be born with blood group O, she must receive O type gene one each from father and mother.
• For this father must have heterozygous A O blood group and mother must have homozygous blood group OO.

Question 6.
How is the sex of the child determined in human beings ?
Answer:
Sex determination : The process by which a person’s sex is determined is called sex determination.

Sex chromosome :

• The chromosomes that determine the sex of a person are called sex chromosomes.
• There are two types of sex chromosomes, one is called the X chromosome, and the other is called the Y chromosome.
• The male has one X chromosome and one Y chromosome.
• This means that half the male gametes or half the sperms will have X chromosomes, and the other half will have Y chromosomes.
• A female has two X chromosomes.
• This means that all the female gametes called ova or eggs will have only X chromosomes.
• If the sperm which have Y chromosome fuse the ovum the result is XY . So its male baby.
• If the sperm which have X chromosome fuse the ovum the result is XX . So its female baby.

AP Board Solutions Class 10 Biology Chapter 8 Questions and Answers (Lab Activities)

Activity – 8.1

Observe the ears of all the students in the class. Prepare a list of students having free or attached earlobes and calculate the percentage of students having each. Find out about the earlobes of the parents of each student in the class. Correlate the earlobe type of each student with that of their parents. Based on this evidence, suggest a possible rule for the inheritance of earlobe types.

S.no.	Name of the student	Free ear lobe	Attached lobe	In the mother	In the father
1.	Y. Chandra	yes	no	no	yes
2.	A. Jyothi	no	yes	yes	yes
3.	K. Srinu	yes	no	yes	no
4.	M. Anjali	yes	no	yes	yes
5.	K. Chandrika	yes	no	no	yes
6.	S. Bhanu	no	yes	no	no
7.	B. Vineel	yes	no	yes	yes
8.	D. Raju	yes	no	yes	no
9.	B. Gopi	yes	no	no	yes
10.	G. Ramesh	no	yes	no	yes

My conclusions:

• Most of my classmates have lobed ears.
• The percentage of lobed ears are 70 %.
• Attached lobes are less.
• These percentage is only 30%.
• I found that classmates character are seen in their parents may be mother or father.
• According to this characters are transmitted from their parents.
• Some times we can see the character in their parents. My teacher said it may transmitted from their grandparents and receive in their parent generation.

Activity – 8.2

In Fig. 8.3, what experiment would we do to confirm that the F2 generation did in fact have a 1:2:1 ratio of TT, Tt and tt trait combinations ?

• This is the Mendel’s monohybrid experiment.
  In F2 generation the phenotype ratio is 3:1,it means 3% of plants are tall and 1% plants are short.
• But the genotype ratio is 1: 2: 1.
• It means homozygous tall are : 1 %
  Heterozygous tall are : 2 %
  Homozygous, short are : 1 %
• This combination explains the law of domination.
• It means in heterozygous condition only one character is expressed, that deminates the next one. Thats why we got 3 % tall plants in this experiment.