Class 10 Biology Chapter 1 Important Questions Kerala Syllabus Genetics of Life

A thorough understanding of Class 10 Biology Notes Kerala Syllabus Chapter 1 Important Questions Genetics of Life can improve academic performance.

SSLC Biology Chapter 1 Important Questions Genetics of Life

Genetics of Life Class 10 Important Questions

Question 1.
Select the correct answer.
Statement 1 : Gene editing process which can bring desirable changes in the genes in DNA.
Statement 2 : The Nobel Prize of 2020 in Chemistry was shared by Emmanuelle Charpentier and Jennifer A Doudna for their contributions in the field of gene editing.
(A) Statement 1 and statement 2 are correct
(B) Statement 1 and statement 2 are wrong
(C) Statement 1 wrong statement 2 correct
(D) Statement 1 correct statement 2 wrong
Answer:
(A) Statement 1 and statement 2 are correct

Question 2.
The double helix model of DNA was presented by
(A) Emmanuelle Charpentier and Jennifer A Doudna
(B) James Watson and Francis Crick
(C) Gregor Johann Mendel and Erich Von Tschermak
(D) Hugo de Vries and Carl Correns
Answer:
(B) James Watson and Francis Crick

Question 3.
Complete the statement.
………………… are the parts of a chromosome which are connected by means of centromere.
Answer:
Chromatids

Question 4.
Select the correct statement.
(a) The DNA in each chromosome is about 2 inches long.
(b) If DNA from 46 chromosomes of a human cell joins together, it would be around 16 feet in length.
(c) If the DNAs of all the cells joins together, it . would be about 670 billion (one billion = 100
crore) miles in length.
Answer:
(a) The DNA in each chromosome is about 2 inches long.

Question 5.
The nitrogen base absent in RNA.
a) Adnine
b) Thymine
c) Uracil
d) Cytosine
Answer:
b) Thymine

Question 7.
Which are the two types of nucleic acids?
Answer:
DNA, RNA

Question 8.
What is the figure shows?

a) a DNA molecule
b) a RNA molecule
c) a nucleotide
d) a chromosome
Answer:
c) a nucleotide

Question 9.
A portion of DNA molecule is shown below. Find out the missing nitrogen base pair from those given below.

Answer:
(b) C – G

Question 10.
Find the word pair relationship and fill in the blanks appropriately.
a) DNA : Thymine
RNA : …………………
b) Adenine : Thymine
Guanine : ………………….
Answer:
a) Uracil
b) Cytosine

Question 11.
Identify the word pair relationship and fill in the blanks:
Female : 44 + XX
Male : ………………….
Answer:
44 + XY

Question 12.
Identify the diagram and mention its importance.

Answer:
Chromosome; Genes present in the chromosomes determine the characters and control traits in all organisms.

Question 13.
Complete the flowchart illustrating the location of gene by using the information given in the box:
nucleus, gene, DNA, cell, chromosome

Answer:
A – Cell
B – Nucleus
C – Chromosome
D – DNA

Question 14.
Select the correct answer.
Statement 1 : During translation mRNA is formed from a specific nucleotide sequence (gene) in DNA.
Statement 2 : The proteins are synthesised as a result of the action of genes.
(A) Statement 1 and statement 2 are correct (B) Statement 1 and statement 2 are wrong
(C) Statement 1 wrong statement 2 correct (D) Statement 1 correct statement 2 wrong
Answer:
(C) Statement 1 wrong statement 2 correct

Question 15.
Complete the statement.
Stages of protein synthesis are …………………… and …………………… .
Answer:
Transcription, Translation

Question 16.
Which is the activity that takesplace in nucleus.
(a) tRNAs carry specific amino acids to the ribosome.
(b) mRNA is formed.
(c) Combine amino acids to make protein.
Answer:
(b) mRNA is formed.

Question 17.
Select the correct answer
Statement 1 : A dominant allele cannot fully hide the allele of the recessive trait in Co-dominance
Statement 2 : Difference in skin colour is due to Multiple allelism.
(A) Statement 1 and statement 2 are correct
(B) Statement 1 and statement 2 are wrong
(C) Statement 1 wrong statement 2 correct
(D) Statement 1 correct statement 2 wrong
Answer:
(B) Statement 1 and statement 2 are wrong

Question 18.
Identify the word pair relationship and fill the missing word. Mention the relation among the pairs.
Roan coat pattern, found on some cattle and horses : Co-dominance :: Blood group in human beings : ……………………..
Answer:
Multiple allelism, Types of Non Mendelian Inheritance and examples

Question 19.
The father of genetics?
Answer:
Gregor Johann Mendel

Question 20.
Mendel conducted the process of hybridization using one pair of contrasting characters. In all his experiments only one character was expressed. In the first generation. So which was the method he adopted to find out recessive character?
Answer:
Mendel self pollinated the plants obtained as the first generation.

Question 21.
When Mendel conduted experiment using one pair
of contrasting characters, the plants obtained in the F2 generation is was in ……………………… ratio.
Answer:
3 : 1

Question 22.
Find out the dominant characters in plants having TTRR, TTRr, TtRR, TtRr traits.
Answer:
All plants are tall with red flowers.

Question 23.
Hereditary factors which Mendel had described are now known as ……………………
Answer:
Genes

Question 24.
“Offsprings of the same parents show differences among themselves” Give reasons for this?
Answer:
During fertilization alleles from the chromosomes of gametes segregate and causes change in the allele combination. This change causes variations in the offsprings. So offsprings of the same parents also show differences.

Question 25.
Identify the picture? From where is it seen?

Answer:
DNA molecule. DNA molecules are seem in chromosome.

Question 26.
Identify the genetic processes responsible for variations

Answer:
Crossing over

Question 27.
Vipin wrote the following as situations that create variations in organisms. Choose the right ones.
a) Mutation
b) Formation of mRNA
c) Crossing over of chromosomes
d) Action of rRNA
Answer:
a) Mutation, c) Crossing over of chromosomes

Question 28.
Observe the illustration and answer the questions given below.

(a) Identify the illustration.
(b) Complete the illustration.
Answer:
(a) Position of DNA
(b) A – Chromosome B- DNA

Question 29.
The statements related to chromosomes in humans are given below. Select the correct statements.
(a) In human beings there are 22 pairs of somatic chromosomes.
(b) There are 46 chromosomes in human beings.
(c) Sex chromosomes are of two types.
(d) Males have two X chromosomes and females have one X chromosome and one Y chromosome.
(e) The genetic makeup of female is 44 + XY.
(f) The genetic makeup of male is 44 + XY.
Answer:
(b) There are 46 chromosomes in human beings,
(c) Sex chromosomes are of two types.
(f) The genetic makeup of male is 44 + XY.

Question 30.
Arrange the following statements suitably in the table given below,
(a) Combine amino acids to make protein.
(b) tRNAs carry specific amino acids to the ribo-some.
(c) mRNA is formed.
(d) mRNA that has reached the ribosome

Transcription	Translation

Answer:
Transcription – c, Translation – a, b, d

Question 31.
Observe the figure and answer the questions given below.

(a) Identify the RNA.
(b) What is the role of this RNA in protein synthesis?
Answer:
(a) tRNA
(b) tRNA carry specific amino acids to the ribosome based on message in the mRNA.

Question 32.
Observe the picture and answer the questions given below.

(a) Identify the genetic processes responsible for variations.
(b) What are the causes of this process?
Answer:
(a) Mutation
(b) Mutations can be caused by errors during DNA replication, exposure to certain chemicals, radiations, etc

Question 33.
Complete the table.

Non Mendelian Inheritance	Cause
Incomplete Dominance	………….. (a) ………………
……………. (b) ………………	(b) More than one gene controls the colour of the skin.

Answer:
(a) A dominant allele cannot fully hide the allele of the recessive trait.
(b) Polygenic inheritance

Question 34.
Explain each term.
(a) Histone octamer.
(b) Nucleosome
(c) Chromatids
Answer:
(a) DNA and histone proteins are the primary components of a chromosome. Eight histone proteins join together to form a histone octamer.

(b) DNA and histone proteins are the primary components of a chromosome. Eight histone proteins join together to form a histone octamer. DNA strands wind around this octamer to form a structure called nucleosome.

(c) Chromatids are the parts of a chromosome which are connected by means of centromere.

Question 35.
Observe the pictures and answer the questions given below.

(a) Identify the nucleic acids.
(b) How these nucleic acids differ from one another? (Hint: Type of sugar, Nitrogen base)
Answer:
(a) A – DNA B – RNA

(b) DNA
Type of sugar – Deoxyribose sugar
Nitrogen base – Adenine, Thymine, Guanine, Cytosine

RNA
Type of sugar – Ribose sugar
Nitrogen base – Adenine, Uracil, Guanine, Cytosine

Question 36.
Complete the illustration.

Answer:
(a) The mRNA contains messages for protein synthesis.
(b) Carry specific amino acids to the ribosome based on message in the mRNA that has reached the ribosome from the nucleus.
(c) rRNA

Question 37.
Observe the illustration and answer the questions given below.

(a) Identify the illustration.
(b) Identify the stages indicated as (i), (ii).
(c) Identify the parts indicated as A, B.
Answer:
(a) Protein synthesis
(b) (i) Transcription (ii) Translation
(c) A – Amino acid B – Ribosome

Question 38.
Write the difference between – Incomplete Dominance, Polygenic inheritance
Answer:
Incomplete Dominance-A dominant allele cannot fully hide the allele of the recessive trait.

Example – If a red flowered four o’clock plant is hybridised with a white flowered plant, the resulting offspring will have pink flowers.

Polygenic inheritance – More than one gene controls the colour of the skin. The action of these genes cause variation in the production of melanin that causes difference in skin colour.
Example – Difference in skin colour.

Question 39.
Observe the picture and answer the questions given below.

(a) Identify the genetic processes responsible for variations.
(b) Identify the part indicated as (i), What is its peculiarity?
(c) How this process cause variations?
Answer:
(a) Crossing over

(b) Chiasma The chromatids break at this region and the broken segments are exchanged with each other.

(c) During meiosis, pairing of homologous chromosomes (Identical chromosomes inherited from the parents of an organism) takes place. The point of contact of the paired chromosomes is called chiasma. The chromatids break at this region and the broken segments are exchanged with each other.This exchange causes a recombination of alleles. This leads to the appearance of new traits in the offspring.

Question 40.
The process of crossing over of chromosomes that takes place in the initial phase of meiosis is illustrated below. Analyse it and answer the questions.

a) Arrange the stages appropriately.
b) This process brings about variations in offspring. How?
Answer:
a) C, A, B

b)

• Part of a DNA crosses over to become the part of another DNA.
• This causes difference in the distributions of genes.
• When these chromosomes are transferred to the next generation, new characters are expressed.

Question 41.
“While some mutations are harmful, some of them are helpful.” Analyse the statement.
Answer:
This statement is correct. Certain mutations are harmful and some are helpful for survival of the organism. Mutations also leads to evolution.

Question 42.
Offsprings may vary in characters from their parents.
a) What are the reasons of this variation in the light of genetics?
b) How does the changes take place during mieosis cause variations in next generation?
c) How does the chemical substances and the radiations cause variation in characters?
Answer:
a) Crossing over and mutations.

b) When a part of a particular DNA become the part of another DNA, the sequencing of nucleotides in the DNA become differs and hence variation may occur in the offsprings.

c) Mutation may occur due to chemicals and radiations.

Question 43.
Rearrange B and C according to the data given in A.

A Nucleic Acids	B Sugar	C Nitroge Base
i) DNA	Ribosome	Uracil
ii) RNA	Deoxyribose	Amenin Adenine
	Ribose	Thymine

Answer:

A	B	C
Nucleic Acids	Sugar	Nitroge Base
i) DNA	Deoxyribose	Thymine
ii) RNA	Ribose	Uracil

Question 44.
Fill in the blanks in the illustration given below.

Answer:
A) tt
B) t
C) Tt
D) dwarf

Question 45.
Given below is an illustration showing how sex determination takes place in men.

a) Observe the illustration and examine the 4 types of possible offspring. Specify their sex chromosomes.
b) What are the inferences you arrive at from this illustration?
c) What is the probable ratio of the formation of male and female children in men?
d) Which are the sex-determining chromosomes in men?
Answer:
a) [i] and [iii] are female children having XX chromosomes, [ii] and [iv] are male children having XY chromosomes.

b) The sex chromosomes of a male determine the sex of a child. The probability of the formation of male and female children is almost equal [1 : 1].

c) 1 : 1

d) Sex determining chromosomes in men are X . and Y.

Question 46.
Observe the illustration related to protein synthesis and answer the questions.

a) Identify the parts indicated as ‘X’ and ‘Y’
b) What is the role of ‘X’ in this process?
c) What are the processes occur in the part indicated as ‘Y’?
Answer:
a) X – mRNA,
Y- Ribosome

b) ‘X’ in the figure indicates mRNA and the role of mRNA is that it carries the information about the protein to be synthesised and reaches the ribosomes. mRNA is formed from DNA.

c) The part indicated as ‘Y’ is the ribosome, which is present in the cytoplasm of the cell. Ribosomes are protein factories, and their main function is to synthesise proteins inside the cell. Ribosomes will come and bind to the mRNA, which is transported from the nucleus to the cytoplasm for protein synthesis

Question 47.
Observe the illustration and answer the questions. (MODEL 2020)

a) Identify the alleles in the first-generation plant related to the trait of tallness.
b) What may be the characters expressed in the second-generation plants?
c) Why do the characters which are not expressed in parents appear in offspring?
Answer:
a) T – Tallness, t – dwarfness

b) 1. Tall plant, round seed
2. Tall plant, wrinkled seed
3. Dwarf plant, round seed
4. Dwarf plant, wrinkled seed

c) When two or more characters are combined together, the factors or genes for each character segregate and assort independently during gamete production and transfer to the next generation.

Question 48.
What is gene editing?
Answer:
A gene editing process which can bring desirable changes in the genes in DNA.

Question 49.
What are the possibilities of gene editing?
Answer:
The discovery of gene editing is expected to make revolutionary advances in genetic disease therapy and treatment of cancer. It can also be used to develop crops that are resistant to pests and diseases.

Question 50.
Where is DNA located?
Answer:
DNA is located in the chromosomes found inside the nucleus.

Question 51.
Who presented the double helical model of DNA?
Answer:
In 1953, James Watson along with Francis Crick had presented the double helical model of DNA. They proposed the structure of DNA based on the X-ray diffraction studies conducted by Rosalind Franklin and Maurice Wilkins.

Question 52.
How was the crucial information that led to the structure of DNA obtained?
Answer:
The crucial information that led to this discovery was obtained from the famous ‘Photo 51’ an X-ray diffraction image of DNA taken by Rosalind Franklin.

Question 53.
Explain the structure of DNA?
Answer:
DNA has a double helix model. As per double helix model of DNA, it has two strands. The strands are composed of sugar and phosphate. The rungs of DNA are formed by the pairing of nitrogen bases. DNA cntain four nitrogen bases – Adenine, Thymine, Guanine, Cytosine. In DNA, the nitrogen base Adenine pairs with Thymine, and Guanine pairs with Cytosine.

Question 54.
What is a nucleotide?
Answer:
Nucleotide is the basic building block of DNA. Each nucleotide is composed of a deoxyribose sugar, a phosphate group, and a nitrogen base.

Question 55.
What are nitrogen bases?
Answer:
Nitrogen base is nitrogen containing alkaline compound.

Question 56.
What is the role of phosphate?
Answer:
The phosphate participates in the formation of bonds that link nucleotides together.

Question 57.
Prepare a short note about the size of DNA.
Answer:
The DNA in each chromosome is about 2 inches
(5cm) long. If DNA from 46 chromosomes of a human cell joins together, it would be around 6 feet in length (2m). The human body is made up of trillions (one lakh crore) of cells. If the DNAs of all the cells joins together, it would be about 67 billion (one billion = 100 crore) miles in length. It is capable enough to wrap around the Earth over two million times.

Question 58.
What is the structure of a chromosome?
Answer:
DNA and histone proteins are the primary components of a chromosome. Eight histone proteins join together to form a histone octamer. DNA strands wind around this octamer to form a structure called nucleosome. The chromosomes are formed by packing and coiling numerous nucleosomes and recoiling the chains of nucleosomes. Chromatids are the parts of a chromosome which are connected by means of centromere. Each species possess a specific number of chromosomes.

Question 59.
What are somatic chromosomes?
Answer:
These are chromosomes that control physical characteristics. There are twenty two pairs of somatic chromosomes. A pair of identical chromosomes together form a homologous chromosome. One of these is inherited from the mother and the other from the father.

Question 60.
What are sex chromosomes?
Answer:
These are the chromosomes which are involved in sex determination. They are of two types. X chromosome and Y chromosome. The Y chromosome is comparatively smaller than that of the X chromosome. The SRY gene on the Y chromosome is responsible for the development of testis in the embryo.

Question 61.
What are genes?
Answer:
Genes provide instructions as to how our body should function. Gene is a specific sequence of nucleotides in DNA. Proteins which are synthesised according to the instructions of genes, are responsible for the formation of characteristic features and or controlling metabolic activities.

Question 62.
Prepare a short note on RNA.
Answer:
The nucleic acid RNA (Ribonucleic acid) alsoplays a crucial role in the synthesis of proteins. RNA is another type of nucleic acid, similar to DNA. They are also made up of nucleotides. Each of the nucleotide contains a ribose sugar, a phosphate group, and a nitrogenous base. The nitrogen bases in RNA are Adenine, Guanine, Uracil, and Cytosine. Most of the RNAs have a single strand.

Question 63.
What is Transcription?
Answer:
mRNA is formed from a speific nucleotide sequence (gene) in DNA with the help of various enzymes. The mRNA contains messages for protein synthesis.

Question 64.
What is Translation?
Answer:
tRNAs (transfer RNA) carry specific amino acids to the ribosome based on message in the mRNA that has reached the ribosome from the nucleus. The rRNAs (ribosomal RNA), which are part of ribosomes combine amino acids to make protein.

Question 65.
Write about the different types of RNA involved in protein synthesis and their functions.
Answer:
mRNA( messenger RNA) – The mRNA contains messages for protein synthesis.

tRNAs (transfer RNA) – Carry specific amino acids to the ribosome based on messages in the mRNA that has reached the ribosome from the nucleus.

rRNAs (ribosomal RNA) – The primary component of the ribosome helps in the formation of bonds.

Question 66.
Explain heredity and variation.
Answer:

• Some characteristics of parents are also found in their children.
• It is also common to see certain characters in children which differ from their parents.
• Heredity refers to the transmission of characteristics from parents to their offspring. Variations are characters expressed in offspring, that differ from their parents.
• Genes inherited from parents are responsible for both heredity and variations.

Question 67.
What is genetics?
Answer:
Genetics is the branch of science that deals with genes, heredity, and variation.

Question 68.
Why Gregor Johann Mendel is considered as the father of genetics?
Answer:
Gregor Johann Mendel’s experiments on pea plants (Pisum sativum) and the conclusions he drew out of hybridisation experiments laid the foundation for the field of genetics. Therefore, he is considered as the father of genetics.

Question 69.
Prepare a short note on Gregor Johann Mendel.
Answer:
Gregor Johann Mendel was bom on 20 July, 1822, at Hyncice a small village of Northern Moravia, which is now known as Czech Republic.

After joining the Augustinian monastery at Brno, he became a priest in 1847. Between 1851 and 1853, he attended the University of Vienna where he studied Physics, Mathematics, and Natural sciences, and learned statistical methods to analyse data scientifically.

Question 70.
What were the studies conducted by Gregor Johann Mendel on pea plants?
Answer:
In 1856, Mendel began to conduct hybridisation experiments on pea plants (Pisum sativum) in the garden of his monastery that focused on seven specific characters such as the colour of flower, shape of the seed etc. Based on the analysis of the experimental result, he explained that a pair of factors controls each character and represented those factors using symbols. These factors are now known to be genes. Gregor Mendel’s conclusions are known as the Laws of Inheritance. These laws provide the fundamental genetic framework to understand heredity and variation.

In 1865, he presented his findings in the Natural History Society at Brno. The following year, he published a thesis titled ‘Experiments on Plant Hybridisation.’ However, the scientific community of that time largely ignored Mendel’s discoveries. Gregor Mendel passed away in 1884.

In 1900, sixteen years after his death, botanists Hugo de Vries, Carl Correns, and Erich von Tschermak recognised the significance of Mendel’s research. With this, Mendel’s findings were accepted as the foundation of the science of genetics.

Question 71.
What is monohybrid cross?
Answer:
Mendel initially conducted hybridisation experiments by considering a single pair of contrasting traits. This is known as a monohybrid cross.

Question 72.
Which characteristics did Mendel refer to as factors?
Answer:
Gregor Mendel hypothesised that characters from parents are passed on to offsprings through certain factors that are transmitted through gametes. It was only after Mendel’s period that, these factors were discovered to be genes that are located in chromosomes in the nucleus.

Question 73.
What are alleles?
Answer:
A gene that determines a character can have different forms. These different forms of genes are called alleles. A gene usually has two alleles. In the hybridisation experiment, the different alleles that determine the character of height are represented by T and t. The allele T represents tall and the allele t represents dwarf.

Question 74.
Compare phenotype and genotype.
Answer:
The observable characteristics of an organism are called phenotype, and the genetic constitution responsible for these characteristics are called genotype.

Question 75.
Is dominant character always a phenotype?
Answer:
No. A dominant character refers to a gene (or allele) that can express itself even if only one copy is present. But a phenotype is the visible trait or observable feature of an organism. For example: In pea plants, the gene for tallness (T) is dominant over the gene for dwarfness (t). A plant with the genotype TT or Tt will both be tall. So, even though T is dominant, the phenotype (what we see) is tall.This means that the dominant character (T) may not always be visible as a separate phenotype – it just shows up in the trait (like tallness). The phenotype is the result of genes (both dominant and recessive), but is not the same as a gene.

Question 76.
What are the inferences drawn by Gregor Mendel from monohybrid cross?
Answer:

• A trait is controlled by two factors.
• When a pair of contrasting traits is subjected to hybridisation, only one of the contrasting traits is expressed in the offspring of the first generation and the other remains hidden. The trait that appears in the first generation is called dominant trait and the hidden trait is called recessive trait.
• The trait hidden in the first generation reappears in the second generation.
• When gametes are formed, the factors that determine trait gets separated without mixing.
• The ratio of dominant to recessive traits in the offspring of the second generation is 3 : 1.

Question 77.
What is dihybrid cross?
Answer:
The inheritance of two pairs of contrasting traits of the same plant. This is known as dihybrid cross.

Question 78.
Characters that are not found in the parent plants are found in the second generation. Why?
Answer:
When two or more different traits are combined, each trait is inherited independently to the next generation without mixing each other. (A pair of alleles in an organism does not influence the separation of another pair of alleles.)

Question 79.
Which concepts led to the development of Non-Mendelian Inheritance?
Answer:
Mendel’s laws were the foundation of genetics. However,it could not fully explain the diversity of traits observed in organisms. Later studies about the complex interaction among genes, environment and other factors revealed some of the limitations of Mendel’s laws. This gave rise to the concept of Non-Mendelian Inheritance.

Question 80.
What is Incomplete Dominance?
Answer:
A dominant allele cannot fully hide the allele of the recessive trait.
Example – If a red flowered four o’clock plant is hybridised with a white flowered plant, the resulting offspring will have pink flowers.

Question 81.
What is Co-dominance?
Answer:
Co-dominance – Roan coat pattern, found on some cattle and horses. Both alleles exhibit their traits at the same time.

Question 82.
What is Multiple allelism?
Answer:
Multiple allelism – ABO blood group in humans. The gene that determines blood group in human beings has more than two alleles. Three alleles I^A, I^B and i determine the blood group.

Question 83.
What is Polygenic inheritance?
Answer:
Polygenic inheritance – Difference in skin colour. More than one gene controls the colour of the skin. The action of these genes cause variation in the production of melanin that causes difference in skin colour.

Question 84.
Explore more situations and examples of Non Mendelian Inheritances
Answer:
Pleiotropy: A single gene affects more than one trait or function in the body.
Example – Sickle Cell Anemia, A single gene mutation affects the shape of red blood cells, but also causes symptoms like pain, weakness, and organ damage

Epistasis: Definition: One gene can hide or block the expression of another gene.
Example: Coat colour in Labrador retrievers. There are two genes, one decides colour (B = black, b = brown). Another decides pigment production (E = pigment, e = no pigment). If a dog is ee, it will be yellow, no matter if it has BB or bb. So, gene E controls whether gene B can show up.

Sex – Linked Inheritance
Definition: The X-linked recessive disorder affects blood clotting, mostly seen in males (XY) because they inherit only one X chromosome.
Example: Hemophilia in Humans

Question 85.
What is a chiasma, and what happens at this region?
Answer:
A chiasma is the point of contact between paired homologous chromosomes where crossing over occurs. At the chiasma, the chromatids break, and segments are exchanged between the non-sister chromatids of homologous chromosomes.

Question 86.
Compare and contrast crossing over and mutation as sources of genetic variation.
Answer:
Similarities: Both crossing over and mutation are processes that introduce new genetic variation into populations. This variation is crucial for adaptation and evolution.

Differences: Crossing over involves the exchange of genetic material between existing homologous chromosomes during meiosis, resulting in new combinations of alleles. Mutation, on the other hand, is a change in the DNA sequence itself, creating entirely new alleles or altering existing ones. Crossing over occurs during sexual reproduction, while mutations can occur in both sexual and asexual reproduction.

Question 87.
What are homologous chromosomes, and why is their pairing important for crossing over?
Answer:
Homologous chromosomes are pairs of identical chromosomes inherited from the parents of an organism. Their pairing is essential for crossing over because the exchange of genetic material occurs between these paired chromosomes.