16
Heredity and Variation
IMPORTANT POINTS The branch of biology which studies the the next, and genes in particula Organams produced by anual reprodu al reproduction, show comparati ed heredity: Transfer of characteristics from parental collinstoned DNA Deoxyrib The segment of DNA which contains all the information for synim of a partic a gene Information necessary for protein synthe The structure in the nucleus of cells that carries the hereditary charse mosome ▸ Chromosomes are of four types: (1) Metacentne (2) Sub-metacentric (3)A Telocentric ▸ Watson and Crick produced a model of the DNA structure Two parallel threads made otides are coiled around each other. This arrangement is called as double helix. Each is made up of a nitrogen base, phosphoric acid and a sugar molecule. There are fo nitrogen bases, adenine, guanine, cyline and thymine Aderune is always paired w and guanine is always paired with cytosine ➤ RNA (Ribonucleic acid) is another important nucleic acid in the cell. These are made sugar, phosphate molecule and four types of nitrogen bases Adenine, guanine, cytos
****SPECIMEN QUESTIONS
(1) The structure in the nucleus of cells that carries the hereditary characteristics is called (1) nucleolus
(2) protoplasm
(3) nuclear membrane
(4) Chromosome
Explanation: The structure in the nucleus of cells that carries the hereditary characteristics is called chromosome.
Option 4 is correct.
2) In the disorder our body cannot produce pigment melanin.
(1) albinism
(2) sickle cell anaemia
(3) Turner syndrome
(4) Down syndrome
Explanation: In the disorder albinism, our bodycannot produce pigment melanin
.Option is correct.
(4) The phenotypic ratio in the second filial generation in Mendel's dihybrid cross experiment was found to be
(1) 1:2:1
(2) 9:3:3: 1
(3) 9:3
(4) 2:5:3
Explanation: The phenotypic ratio in the second filial generation in Mendel's dihybridcross experiment was found to be 9.3.3.1.
Option (2) is correct.
QUESTIONS FOR PRACTICE
(1) The harmful effects of tobacco are mainly due to present in it.
(1) proteins
(2) fats
(3) nicotine
(4) hormoneof
Ana-(3) nicotine
(2) Chromosomes are mainly made up of -
(1) DNA
(2) RNA
(3) proteins human cells there
(4) lipids are
Ana- (1) DNA
(3) In chromosomes.
(1) 48
(2) 44
(3) 50
(4)46
Ana-(4)46
4) In the disorder chromosomes instead of 46. there are 47
(1) Tumer syndrome
(2) Down syndrome
(3) Klinefelter syndrome
(4) sickle cell anaemia
Ana-(4) sickle cell anaemia
(5) Which of the following disorders are caused due to the abnormalities of chromosomes?
(A) Down syndrome
(B) Albinism
(C) Tumer syndrome
(D) Sickle cell anaemia
(1) A and B
(2) B and C
(3) A and C
(4) A and D
Ana-(3) A and C
(6) Which of the following is not a syndrome of sickle cell anaemia?
(1) Pain in joints
(2) Absence of melanin
(3) Frequent colds and cough
(4) low haemoglobin content
Ana-(2) Absence of melanin
(7) Which of the following statements is wrong? (A) Mendel's principles form the basis of modern genetics. (B) A segment of RNA is called a gene. (C) In acrocentric chromosome, the centromere is exactly at the midpoint of chromosome. (D) There are 23 pairs of chromosomes in the human cells
. (1) A and B
(2) B and C
(3) C and D
(4chromosome
Ana-(2) B and
(8) Telocentric chromosome: letter i :: Metacentric chromosome: letter-
(1)X
(2) Y
(3) L
(4)XXYA
Ana-(4) V
(9) 44+ X: Turner syndrome :: 44+ XXY:
(1) Down syndrome.
(2) Albinism.
(3) Klinefelter syndrome.
(4) Sickle cell anaemia.
Ana-(3) Klinefelter syndrome.
(10) is not a type of RNA
. (1) rRNA
(2) mRNA
(3) XRNA
(4) tRNA
Ana-(3) XRNA
(11) The phenotypic ratio in the second filial generation in the experiment of Mendel's monohybrid cross was
(1) 1:1:1:1
(2)3:1
(3) 9:3:3:1
(4) 1:2:1
Ana-(2)3:1
(12)In sickle cell anaemia, the___amino acidis replaced by another.
(1)6
(2) 3rd
(3) 5th
(4) 13th
Ana-(1)6
(13) performs the function of protein synthesis.
(1) Mitochondria
(2) mRNA
(3) TRNA
(4) tRNA
Ana-(3) TRNA
(14) As per the scientists, there are about- genes in the human genome.
(1)20-30 thousand
(2) 40-50 thousand
(3) 2-3 thousand
(4) 20-30 million
Ana-(1)20-30 thousand
(15) In the structure of DNA, adenine always pairs with
(1) adenine
(2) cytosine
(3) guanine
(4) thymine
Ana-(4) thymine
(16) The allosomes in human females can be represented as
(1)XX
(2)XY
(3) YY
(4)XYX
Ana-(1)XX
(17) Which of the following is not a constituent of a DNA?
1) Adenine
(2) Cytosine
(3) Uracil
(4) Thymine
Ana-(3)Uracil
(18) Constricted region on chromosome is called as
(1) arm
(2) gene of
(3) nitrogen base
(4) centromere
Ana-(4) centromere
(19) is not a type of chromosomes.
(1) Polycentric
(2) Metacentric f
(3) Acrocentric
(4) Telocentric
Ana-(1) Polycentric
(20) Potato cells have number of chromosomes.
(1)46
(2) 44
(3) 48
(4)23
Ana-(3) 48
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