10th Science Unit 18 Book Back Answer

Samacheer Kalvi 10th Science Unit 18 Book Back Questions with Answers:

Samacheer Kalvi 10th Std  Science Book Back 1 Mark and 2 Mark Questions with Answers PDF in Science uploaded and available below. 10th Standard New Science Syllabus 2022 – Biology 18 Heredity Science Book Back Answers available for both English and Tamil mediums. Tamil Nadu Samacheer Kalvi 10th Science Book Portion consists of  23 Units. Science Book Contain Physics 01- 06, Chemistry 07 – 11, Biology 12 – 22 and Visual Communications  23 units. Check Unit-wise and Full Class 10th Science Book Back Answers/ Guide 2022 PDF format for Free Download for both English and Tamil Medium. Samacheer Kalvi 10th Science Book back Solutions/Answers below:

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Samacheer Kalvi 10th Science Book Subject One Mark, Two Mark Guide questions and answers are available below. Check Science Book Back Questions with Answers. Take the printout and use it for exam purposes.

10th Science Book Back Answers

Unit 18 – Heredity

I. Choose the best answer:

1. According to Mendel alleles have the following character
a) Pair of genes                     b) Responsible for character
c) Production of gametes    d) Recessive factors
Ans : (b) Responsible for character

2. 9 : 3 : 3 : 1 ratio is due to
a) Segregation                            b) Crossing over
c) Independent assortment     d) Recessiveness
Ans : (c) Independent assortment

3. The region of the chromosome where the spindle fibers get attached during cell division
a) Chromomere   b) Centrosome   c) Centromere   d) Chromonema
Ans : (c) Centromere

4. The centromere is found at the center of the chromosome.
a) Telocentric b) Metacentric c) Sub-metacentric d) Acrocentric
Ans : (b) Metacentric

5. The units form the backbone of the DNA.
a) 5 carbon sugar   b) Phosphate   c) Nitrogenous bases   d) Sugar phosphate
Ans : (d) Sugar phosphate

6. Okasaki fragments are joined together.
a) Helicase   b) DNA polymerase   c) RNA primer   d) DNA ligase
Ans : (d) DNA ligase

7. The number of chromosomes found in human beings are.
a) 22 pairs of autosomes and 1 pair of allosomes    b) 22 autosomes and 1 allosome
c) 46 autosomes    d) 46 pairs of autosomes and 1 pair of allosomes
Ans : (a) 22 pairs of autosomes and 1 pair of allosomes.

8. The loss of one or more chromosomes in ploidy is called.
a) Tetraploidy b) Aneuploidy c) Euploidy d) polyploidy
Ans : (b) Aneuploidy

II. Fill in the blanks

1. The pairs of contrasting character (traits) of Mendel are called.  Ans: Allele or allelomorphs

2. Physical expression of a gene is called Ans : Phenotype

3. The thin thread-like structures found in the nucleus of each cell are called.  Ans: Chromosomes

4. DNA consists of two chains. Ans: Polynucleotide

5. An inheritable change in the amount or the structure of a gene or a chromosome is called.  Ans: Mutation




III. True or False (Correct the Statement if it is false)

1. A typical Mendelian dihybrid ratio of F2 generation is 3:1.
Ans: False. A typical Mendelian dihybrid ratio of F2 generation is 9 : 3: 3: 1.

2. A recessive factor is altered by the presence of a dominant factor.
Ans: False. A recessive factor is masked by the presence of a dominant factor.

3. Each gamete has only one allele of a gene. Ans: True.

4. Hybrid is an offspring from a cross between genetically different parents. Ans: True.

5. Some of the chromosomes have an elongated knob-like appendage known as telomere.
Ans: False. Some of the chromosomes have an elongated knob-like appendage known as Satellite.

6. New nucleotides are added and a new complementary strand of DNA is formed with the help of the enzyme DNA polymerase.
Ans: True

7. Down’s syndrome is a genetic condition with 45 chromosomes.
Ans: False. Down’s syndrome is a genetic condition with 47 chromosomes.

IV. Match the following:

Question:

Column A Column B
1. Autosomes (a) Trisomy 21
2. Diploid condition (b) 9 : 3 : 3 : 1
3. Allosome (c) 22 pair of chromosome
4. Down’s syndrome (d) 2n
5. Dihybrid ratio (e) 23rd pair of chromosome

Answer:
1. (c) 22 pairs of chromosome
2. (d) 2n
3. (e) 23rd pair of chromosome
4. (a) Trisomy 21
5. (b) 9 : 3 : 3 : 1

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