Unit 4: Heredity
Multiple
Choice Questions: [ 1 mark each]
1. The
branch of biology that deals with the study of genes is called ………………
a) heredity b) inheritance c)
genetics d) genealogy
2. Who
is known as the father of genetics?
a) Charles
Darwin b) Lamarck c) Hugo de Varies d)
G. J. Mendel
3. What
is the term used to describe an individual with two different alleles for a
particular gene?
a) Heterozygous b) Homozygous c) Dominant d) Recessive
4. What
is the term used to describe the genetic makeup of an individual?
a)
Phenotype b)
Genotype c) Homozygous d) Heterozygous
5. Cell
is made up of …………………..
a) protoplasm b) cell organelles c) cell inclusions d) all of these
6. Which
of the following organism reproduces by amitosis cell division?
a) amoeba b) starfish c)
snail d)
None of these
7. A
zygote is unicellular. Which cell division changes it into the multicellular
structure?
a) amitosis b) mitosis c) binary fission d)
meiosis
8. Which
of the following pair has double hydrogen bond between them?
a) A and G b) A and C c)
G and C d) A and T
9. Which
of the following base pair has triple hydrogen bond between them?
a) A and G b) A and C c)
G and C d) A and T
10. What
is the diameter of one DNA molecule?
a) 200 A b) 340
A c) 300
A d) 3.40
A
11. What
is the distance between one complete spiral of DNA?
a) 200 A b) 340
A c) 300
A d) 3.40
A
12. How
many pairs of nitrogen bases are found in one spiral of DNA?
a) 10 b) 20 c)
30 d) 40
13. Who
coined the tem genetics?
a) Mendel b) Morgan c)
Darwin d) Whittaker
14. w
Answers: 1(c), 2(d), 3 (a), 4(b), 5(d), 6(a), 7(b), 8(d),
9(c), 10(a), 11(b), 12(a), 13(a)
Very
short Answer Questions [1 mark
each]
1. What
is cytology?
The branch of biological science
which deals with the study of cell is called cytology.
2. What
is a cell?
A cell is the structural and
functional unit of life.
3. Where
are chromosomes located?
Chromosomes are located inside the
nucleus of a cell.
4. What
is full form of DNA?
The full form of DNA is
Deoxyribonucleic acid.
5. What
are chromosomes?
Chromosomes are long, coiled-up
strands of DNA that contain the genetic information or hereditary material of
an organism.
6. Define
diploid cell.
A diploid cell is a
cell that contains two complete sets of chromosomes. All
somatic cells or vegetative cells are diploid cells.
7. What
do you mean by haploid cell?
The cell that contains a single set
of chromosomes are called haploid cells. All reproductive cells (gametes) are
haploid in nature.
8. What
is cell division?
Cell division is a biological
process of division of single mother cell to form daughter cell.
9. Define
amitosis cell division.
Amitosis is a type of cell division
in which a cell divides into two or more cells simply by the division of
nucleus and cytoplasm.
10. What
is mitosis cell division?
Mitosis is the type of cell
division in which a single mother cell divides into two identical daughter cell
with the division of chromosome and cytoplasm.
11. Who
discovered mitosis cell division?
A German biologist Walter Flemming
discovered mitosis cell division in 1882.
12. Who
discovered meiosis cell division?
A German biologist Oscar Hertwig discovered
meiosis cell division in 1876.
13. What
are the two main stages of cell division?
The two main stages of cell
division are Karyokinesis and Cytokinesis.
14. What
is karyokinesis?
The division of nucleus during a
cell division is called karyokinesis.
15. What
is cytokinesis?
The division cytoplasm of a cell
during or after karyokinesis is called cytokinesis.
16. What
are the phases of mitosis cell division?
The phases of mitosis cell division
are prophase, metaphase, anaphase and Telophase.
17. What
is the difference between meiosis I and meiosis II?
The difference between meiosis I
and meiosis II is that meiosis I is reductionaldivision in which the diploid
number of chromosome (2n) is reduced to haploid (n) but in meiosis II haploid
(n) chromosomes undergo equational
division forming 4 haploid cells.
18. What
is chromatid?
A chromatid is one half of a
replicated chromosome formed during both the mitosis and meiosis cell division.
19. Define
chromatin fibre.
Chromatin fibre is an uncoiled and
uncondensed mass of chromosome.
20. What
is centromere or kinetochore?
The centromere is the region of the
chromosome that holds two sister chromatids together after the replication of
the chromosome.
21. What
is secondary constriction?
Secondary
constrictions are the constricted or the narrow region for the nuclear
organization found at any point of the chromosome other than that of centromere
(primary constriction).
22. Define
telomere?
Telomere is defined
as the terminal region of each side of chromosome.
23. What
is Chromonema?
Chromonema is a term
that refers to the highly coiled and condensed structure of DNA within a
chromosome during cell division.
24. What
are chromomeres?
They are small
beadlike structures that pair during meiosis in many organisms, and are visible
in a chromosome when it is relatively uncoiled, in particular at the leptotene
and zygotene stages of meiosis.
25. What
is gene?
A gene is the basic
physical and functional unit of heredity, made up of DNA.
26. What
is DNA?
DNA (Deoxyribonucleic Acid) is a
molecule that carries genetic instructions for the development, functioning,
growth, and reproduction of all living organisms.
27. What
are the nitrogen bases of DNA?
The nitrogen bases are adenine (A),
guanine (G), Cytosine (C) and thymine (T).
28. Name
the sugar molecule attached with DNA.
The sugar molecule attached with
Nitrogen base is Deoxyribose pentose sugar.
29. What
are autosomes?
Autosomes are the chromosomes other
than sex chromosome. There are 22 pairs of autosomes in human being.
30. What
are sex chromosome?
The chromosome that determine the
sex of an offspring of an organism.
31. What
are the types of sex chromosomes found in male and female of human being?
The types of sex chromosome found
in mare are XY and the sex chromosome found in female are XX.
32. What
is nucleotide?
The combination of nitrogen base,
pentose sugar and phosphate molecule is called nitrogen base.
33. What
is nucleoside?
Nucleoside is the combination of
nitrogen base and Pentose sugar.
34. What
is the full form of RNA?
The full form of RNA is Ribonucleic
acid.
35. How
many types of RNA are there? What are they?
There are three types of RNA. They
are mRNA, tRNA and rRNA.
36. Name
the nitrogen bases of RNA.
The nitrogen bases of RNA are:
Adenine, guanine, cytosine and uracil,
37. Where
are RNA located?
RNA are located mainly is cytoplasm
but it is also found in nucleolus and nucleoplasm.
38. What
is heredity?
Heredity is the process of
transmitting parental characteristics from parents to the offspring.
39. Define
variation.
Variation can be defined as the
differences in the characteristics or behavior of organism among the
individuals of a species.
40. What
is the unit of heredity called?
The unit of heredity is called
gene.
41. What
is locus?
The position of gene in a
chromosome is called locus.
42. What
is an allele?
An allele is any one of the two or
more genes that are found at a particular locus.
43. Define
Homozygous.
When both the alleles of a
particular gene are identical for a trait on both the homologous chromosome,
then the the individual is said to be homozygous for that trait. For example:
TT, tt, RR, rr, etc.
44. What
is heterozygous?
When the alleles of a particular
gene are different for a trait on two homologous chromosome, then the
individual is said to be heterozygous for that trait. For example if an
individual has one allele for curly hair and other allele for straight hair,
then the individual is heterozygous for that trait.
45. Define
dominant and recessive character.
The character or allele of a gene
which is prominent and expressed in heterozygous masking the expressing of its
complementary trait is known as dominant.
The suppressed character or allele
of a gene in a heterozygous is called recessive character.
46. What
is phenotype and genotype?
The external appearance of an
organism for a particular character is called phenotype and the genetic make-up
or genetic constitution of an organism for a particular character is called
genotype.
47. Define
hybrid.
Hybrid is an organism having
different phenotype and genotype. In
other words, the offspring produced after crossing between two genetically
different homozygous individual are called hybrid.
48. Define
hybridization.
The process of crossing or breeding
two individual of an organism having two or more contrasting character.
49. What
is monohybrid cross?
The cross in which single pairs of
contrasting character or allelomorphs are involved is called monohybrid cross.
50. What
is dihybrid cross?
The cross involving two pairs of
contrasting characters or allelomorphs is called dihybrid cross.
51. Define
First filial (F1) generation and Second filial (F2) generation.
The offspring obtained by crossing
between two pure breeding parents is called F1 generation and the
offspring obtained by selfing/interbreeding the parents obtained in F1
generation is called F2 generation.
52. What
is genetics?
Genetics is a
branch of biological science which deals with the study of heredity and nature
and behavior of gene.
53. Write
Mendel's Laws or Mendelism.
Mendel's laws are:
i) Law of dominance
ii) Law of segregation or loaw of
purity of gametes
iii) Law of independent assortment
54. State
Mendel's law of dominance.
Mendel's law of dominance state
that when parents with pure contrasting traits are crossed together, only one
form of trait are expressed in next generation. The hybrid offsprings will
exhibit only the dominant trait in the phenotype.
55. State
of segregation or law of purity of gametes.
Mendel's law of segregation or the
low of purity of gametes states that "The two contrasting members of a
pair of traits (one dominant and other recessive) in a hybrid of F1 generation
separate or segregate at the time of gamete formation."
56. State
the law of independent assortment.
Mendel's law of independent
assortment states that "When the parents differ from each other in two or
more pairs of contrasting characters or traits, then the inheritance of one
pair of factor is independent of the other pair of traits or factors."
57. What
do you mean by heredity variation?
The variation caused due to the
differences in genetic information such as gene expression which passes from
one generation to the next
58. What
is environmental variation?
The variation of an organism due to
the influence of environmental factors such as temperature, chemicals or
nutrition.
59. What
is continuous variation?
The variation that occurs due to
the gradual change in hereditary characters is called continuous variation.
60. What
is discontinuous variation?
The variation that occur by sudden
change in the hereditary characters is called discontinuous variation.
61. Define
mutation.
The sudden change in the genetic
materials of an organism is called mutation.
62. Who
proposed the theory of mutation?
A Dutch biologist Hugo De Varies
proposed the theory of mutation.
63. What
is genetic engineering?
Genetic engineering is a process that uses laboratory-based
technologies to change the DNA makeup of an organism which may involve changing
a single base pair (A-T or C-G), deleting a region of DNA or adding a new
segment of DNA.
64. What
is cloning technology?
Cloning technology is the process
of generating identical copy of a cell or an organism.
65. What
is pre-implantation genetic diagnosis (PGD)?
Pre-implantation genetic diagnosis
(PGD) is a technique used during in vitro fertilization (IVF) to identify
genetic abnormalities in embryos before they are implanted in the uterus.
66. What
do you mean by interspecific breeding?
The cross breeding between any two
individuals of different species is called interspecific breeding. For example
mule is produced by the cross breeding of female horse and male donkey.
67. Define
In-vitro fertilization.
Short
Answer Questions. [2 marks each]
1. Why
is cell called the structural and functional unit of life?
Cells are the basic unit of life
because they are structurally and functionally complete on their own, and they
can carry out all the essential processes required to sustain life.
2. Write
two differences between haploid and diploid cells.
Two differences between haploid and
diploid cells are:
|
Haploid Cells |
Diploid Cells |
|
1. They
have single set of chromosomes. |
1. They
have double sets of chromosomes. |
|
2. They
are produced by meiosis cell division. |
2. They
are produced by mitosis cell divison. |
3. Differentiate
between mitosis and meiosis cell division.
|
Mitosis |
Meiosis |
|
1. It
occurs in somatic or vegetative cells. |
1. It
occurs in reproductive cells. |
|
2. A
single cell produces two identical daughter cells. |
2. A
single cell produces four un-identical daughter cells. |
|
3. There
is a single division. |
3. There
is a double division. |
|
4. Genetic
characters are preserved |
4. Genetic
characters are varied. |
4. Why
is mitosis cell division called equational cell division.
Mitosis cell division is called
equational cell division because the daughter cell produced through mitosis
cell division possess same number of chromosomes to that of the mother cell.
5. Why
is mitosis cell division also called somatic cell division?
Mitosis cell division is also
called as somatic cell division because it occur only in somatic or vegetative
cells of an organism.
6. What
is interphase?
Interphase is a phase in the cell
cycle that occurs prior to cell division. It is a period of growth and DNA
replication that prepares the cell for cell division.
7. What
is chromatin fibre?
Thin long, coiled network of
diffused form of chromosome is called chromatin fibre.
8. Why
is meiosis cell division important?
Meiosis cell division is important
because it plays a vital role in the sexual reproduction, maintain the fixed
number of chromosomes in offspring, brings genetic diversity and contribute in
evolution of new species.
9. How
does crossing over occur during meiosis, and what is its significance?
Crossing over is a cellular process
that happens during meiosis when chromosomes of the same type are lined up.
When two chromosomes — one from the mother and one from the father — line up,
parts of the chromosome can be switched. The two chromosomes contain the same
genes, but may have different forms of the genes. Crossing over is significant
because it brings genetic diversity and variation among the offspring of same
individuals.
10. Draw
a well labeled diagram of chromosome.
1. What
are the functions of rRNA, tRNA and mRNA?
The main
function of rRNA is to form basic component for ribosome. tRNA carries amino
acid molecule to the ribosome for protein synthesis and mRNA carries genetic
information from DNA and help to protein synthesis.
2. Write
any two functions of gene.
The functions of
gene are:
a)
Gene are
responsible for the inheritance of characteristics from one generation to
another.
b)
They code for
proteins to control phenotype and metabolism.
c)
Genes help in
evolution by mutation and genetic recombination.
d)
Genes can be
activated or deactivated in response to environmental stimulus.
3. Why
is Mendel known as the father of genetics?
Mendel is known
as the father of genetics because of his pioneering work on the inheritance of
traits in pea plants, which laid the foundation for the modern science of
genetics.
4. Write
the differences between phenotype and genotype
|
Phenotype |
Genotype |
|
1.
Phenotype is
the morphological appearance of an organism. |
1.
It is the
genetic expression of an organism. |
|
2.
Phenotype may
change by environmental factors. |
2.
It does not
vary with environmental factors. |
|
3.
Organism with
different phenotype are with different genotype. |
3.
Organism with
different genotype may have similar phenotype |
|
4.
For example: a
red flowered pea and white flowered pea plant may have different genotype Rr,
rr |
4.
For example: a
red flowered pea plant has genotype Rr, RR |
5. Write
the differences between monohybrid cross and dihybrid cross.
|
Monohybrid |
Dihybrid |
|
1.
It is a cross
between two parents involving a single pairs of contrasting character. |
1.
It is a cross
between two parents involving two pairs of contrasting characters. |
|
2.
Monohybrid
cross is determined by law of inheritance or law of dominance. |
2.
It is
determined by law of independent assortment. |
|
3.
The phenotype
ratio in F2 generation is 3:1 |
3.
The phenotype
ratio in F2 generation is 9:3:3:1 |
6. Differentiate
between RNA and DNA
|
RNA |
DNA |
|
1.
It is single
stranded. |
1.
It is double
stranded. |
|
2.
It transfer
parental characters to the offspring. |
2.
It synthesizes
protein. |
|
3.
Its nitrogen
bases are adenine, thymine, cytosine, and guanine. |
3.
It nitrogen
bases are adenine, uracil, cytosine and guanine. |
|
4.
It has deoxyribose
sugar. |
4.
It has ribose
sugar. |
7. Write
differences between variation and mutation.
|
Variation |
Mutation |
|
1.
It is the
natural differences existing between two individual of same species. |
1.
It is the
change that occur in the DNA sequence or chromosome of an organism. |
|
2.
Variations are
relatively small changes that occur within the genetic material of an
organism, such as changes in hair color or height. |
2.
Mutations are
usually more significant changes that alter the DNA sequence of a gene or a
chromosome. |
|
3.
Variation
passes from one generation to the next. |
3.
Mutation may
occur spontaneously and may not pass from one generation to the next. |
8. Differentiate
between autosomes and sex chromosomes.
The differences
between autosomes and sex chromosomes are:
|
Autosomes |
Sex
Chromosome |
|
1.
Autosome
determine characters or traits. |
1.
Sex
chromosomes determine the sex of an individual. |
|
2.
Both male and
female has same copy of chromosomes. |
2.
There are
different copies of sex chromosomes in male and female. |
|
3.
There are 22
pairs of autosomes. |
3.
There is a
pair of sex chromosome. |
|
4.
Autosomes are
completely homologous. |
4.
Sex
chromosomes are partially homologous. |
9. Why
did Mendel select pea plant for his experiment?
Mendel selected
pea plant for his experiment because of the following reasons:
a) Pea plant is
naturally self pollinating and artificial cross pollination is also earier to
conduct.
b) It has large
number of contrasting characters like height, colour of flower, colour of
seeds, etc.
c) The hybrid
obtained as a result of cross-pollination are fertile.
d) A large
number of progeny can be obtained in a short period of time.
10. Differentiate
between inbreeding and out breeding.
|
Inbreeding
|
Outbreeding |
|
1.
It is the
process of mating or breeding of genetically close related individuals. |
1.
It is the of
mating or breeding distantly related or unrelated individuals. |
|
2.
It reduces
genetic variation in the progeny. |
2.
It increases
variation in the successive progeny. |
|
3.
inbreed for a
very long generation may lead to the risk of genetic defect and health
problems. |
3.
outbreed has
more chances to have overall fitness of an organism. |
11. Write
the differences between selective breeding and cross-breeding.
|
selective
breeding |
Crossbreeding |
|
1.
selective
breeding or artificial breeding is the process of breeding a plant or animal
for desirable characteristics. |
1.
Crossbreeding
refers to the mating between the individuals of different breed or population
with new combination of traits.. |
|
2.
It is done to create
offspring with desirable character such as improved productivity, disease
resistant, etc. |
2.
It's aim is to
introduce new genetic characters/traits into a population. |
|
3.
It reduces
genetic diversity. |
3.
It increases
genetic diversity. |
12. Write
few advantages of in-vitro fertilization.
a)
increases the
chances of healthy offspring.
b)
Reduction in the
chances of miscarriage.
c)
Genetic disorder
can be easily treated.
d)
People have
fertility issue can have a child by using donor sperm or ovum.
13. What
are the disadvantages of IVF?
a)
Chances of
premature delivery.
b)
Risk of multiple
birth.
c)
IVF is costly.
d)
It may cause
hormonal disorder and medical side-effect.
14. Write
advantages of artificial insemination (AI).
The advantages
of artificial insemination are:
a)
It is a simple,
minimally invasive procedure that does not require any surgery.
b)
Artificial
inseminations can be done at the doctor’s office or at home.
c)
AI has been
found to have success rates as high as 75%.
d)
It is safe for
both the man and woman.
15. Write
few disadvantages of artificial insemination:
The
disadvantages of artificial insemination are:
a)
Requires
well-trained and equipment.
b)
Needs more time
than natural process for the conception.
c)
Requires clean
and sanitized or sterilized equipment.
d)
Semen needs to
be stored safely under the constant temperature of -780C.
Long
Answer Questions. [4 marks
each]
1.
Write any four
significance of cell division.
Four
significance of mitosis cell division are:
a)
It maintain the
total number of chromosome in every generation of an organism.
b)
It helpin growth
and development of an organism.
c)
The wear out and
damaged cells are repaired by the means of cell division.
d)
Both sexual and
asexual reproduction is only possible through cell division.
2.
Write any four
features of mitosis cell division.
The four
features of mitosis cell division are:
a)
A single diploid
cell (2n) divides into two diploid daughter cells.
b)
There are four
phases of karyokinesis i.e. prophase, metaphase, anaphase and telophase.
c)
The daughter
cells produced are identical to that of mother cell.
d)
It occurs in
somatic or vegetative cells.
3.
What are the
changes that occur in a cell during interphase?
The following
changes occur in a cell during cell division.
a)
The size of cell
and nucleus increases.
b)
Storage of
nutrient required for cell division takes place.
c)
Nucleus,
nucleolus and nuclear membrane are clearly visible.
d)
Replication of
DNA occur.
e)
Chromosome
become long, thin, coiled thread like network called chromatin fibre.
4.
State the major
changes that occur in a cell during prophase of mitosis.
Prophase is the first stage of
karyokinesis. The major changes that occur in this phase are:
a) The
nuclear membrane and nucleolus disappear.
b)
c) Chromosomes
becomes short and thicker.
d) Centrosome
of animal cell divides into two centrioles.
e) Centrioles
start to move towards opposite poles.
f) Spindle
fibres get attached with centromere of chromosome.
5.
Draw a well
labeled diagram of metaphase and write the major changes that occur in this
phase.
a) Chromosomes
become shorter, thicker and more distinct.
b) The
centrioles reach at the respective opposite poles.
c) All
the chromosomes get arranged in the equatorial plane of the cell.
d) Spindle
fibre attached with centromere of each of the chromosome.
6.
With a well
labeled diagram explain the changes occur during Anaphase of mitosis.
a) During
anaphase of mitosis, the sister chromatids, which were held together by the
centromere, begin to separate and move towards opposite poles of the cell.
b) As
the sister chromatids separate, the cell elongates and the poles move further
apart.
c) t
the end of anaphase, each pole of the cell contains a complete and identical
set of chromosomes.
7.
Features of telophase are:
Telophase is the final
stage of mitosis, the process by which a eukaryotic cell divides into two
identical daughter cells. During telophase, several key events occur,
including:
a) The
spindle fibers that have pulled the chromosomes apart during the previous stage
(anaphase) continue to move the chromosomes toward opposite poles of the cell.
b) Once
the chromosomes reach their respective poles, a nuclear membrane begins to form
around each set of chromosomes. These membranes will eventually separate the
cell into two daughter cells.
c) The
condensed chromosomes begin to uncoil and return to their more relaxed state.
d) Cytokinesis
is the process by which the cytoplasm of the cell is divided between the two
new daughter cells. In animal cells, a cleavage furrow forms, pinching the cell
in two. In plant cells, a cell plate forms along the center of the cell, which
eventually becomes the cell wall.
8.
Write any four
significance of mitosis cell division.
e) Mitosis
is important for the growth and development of organisms.
f) Mitosis
plays a critical role in tissue repair and regeneration. When tissues are
damaged, mitosis allows for the replacement of damaged cells with new cells,
ensuring the proper functioning of the affected tissue.
g) In
some organisms, mitosis is the primary method of reproduction. In these
organisms, a single cell can divide and produce identical offspring. This is
known as asexual reproduction. It also has a significant role in vegetative
propagation.
h) During mitosis, the chromosomes are duplicated
and then divided evenly between the daughter cells. This ensures that each
daughter cell has the same number of chromosomes as the parent cell, and helps
to maintain the stability of the organism's genome.
9.
What are the
stages of meiosis, and what happens during each stage?
Meiosis is a
type of cell division that occurs in sexually reproducing organisms. It
involves two rounds of division that result in the production of four
genetically diverse haploid cells from one diploid cell. The stages of meiosis
are as follows:
a)
Prophase I:
Chromosomes condense, and homologous pairs come together in a process called
synapsis. This allows for the exchange of genetic material between the
chromosomes in a process called crossing over.
b)
Metaphase I:
Homologous pairs of chromosomes align at the equator of the cell, and spindle
fibers attach to the chromosomes.
c)
Anaphase I:
Homologous chromosomes separate and move to opposite poles of the cell.
d)
Telophase I:
Chromosomes arrive at the poles of the cell, and the cell divides in a process
called cytokinesis, forming two haploid daughter cells.
e)
Prophase II:
Chromosomes condense again, and the spindle apparatus forms.
f)
Metaphase II:
Chromosomes align at the equator of the cell, and spindle fibers attach to the
chromosomes.
g)
Anaphase II:
Sister chromatids separate and move to opposite poles of the cell.
h)
Telophase II:
Chromosomes arrive at the poles of the cell, and the cell divides in a process
called cytokinesis, forming four haploid daughter cells.
10. What are the significance of meiosis cell division?
Meiosis cell
division has following significance:
a)
It is responsible
for the formation of sex cells or gametes.
b)
It maintains the
constant number of chromosomes in sexually reproducing organisms.
c)
Crossing over
produces new combination of traits and variation in the characteristics of
organisms.
d)
It is also responsible
for the evolution of new organism.
11. Explain the types of chromosomes on the basis of
position of centromere with illustration.
There are four
types of chromosomes on the basis of position of centromere. They are:
a)
Metacentric
chromosome: It is the chromosome in which the centromere is located in the
middle of the chromosome resulting equal arms. Example: chromosome 1 and 3 of
human being.
b)
Sub-metacentric:
If the centromere is located slightly away from the middle or center then it is
called sub-metacentric chromosome.
c)
Acrocentric
chromosome: It is the chromosome in which centromere is located towards the end
of chromosome so that one arm is very short and other is very long.
d)
Telocentric
chromosome: The chromosome in which centromere is located at one of the end of
the centromere.
1.
Draw a well
labeled diagram of DNA.
1.
Describe the
structure of DNA.
The DNA structure can be thought of as a twisted
ladder which is called as a double-helix. It is a nucleic acid, and all nucleic
acids are made up of nucleotides. The DNA molecule is composed of units
called nucleotides, and each nucleotide is composed of three
different components such as sugar, phosphate groups and nitrogen bases. The
sugar and phosphate groups link the nucleotides together to form each strand of
DNA. Adenine (A), Thymine (T), Guanine (G) and Cytosine (C) are four
types of nitrogen bases. A always paired with T, and C paired
with G. These base pairs are essential for the DNA’s double helix
structure, which resembles a twisted ladder. Deoxyribose sugar form the
backbone of DNA. The pitch of each helix is 3.4 nm. Hence, the distance
between two consecutive base pairs (i.e., hydrogen-bonded bases of the opposite
strands) is 0.34 nm.
2.
Write any four
differences between DNA and RNA.
|
DNA |
RNA |
|
1.
DNA is found
in chromosome. |
1.
RNA is found in
cytoplasm |
|
2.
It has
deoxyribose sugar. |
2.
It has ribose
sugar. |
|
3.
It is
responsible for the transmission of genetic characters from parents to
offspring. |
3.
It is
responsible for protein synthesis. |
|
4.
It is double
stranded helically coiled structure. |
It
is single stranded structure. |
|
5.
It undergo
replication. |
4.
It does not
replicate. |
3.
Write the
differences between Tigon and Liger
|
Tigon |
Liger |
|
1.
Tigon is the
cross-breeded offspring produced by the cross between male tiger and female
lion. |
1.
Liger is the
organism obtained from the cross between male lion and female tiger. |
|
2.
It is smaller
than liger. |
2.
It is larger
than Ligon. |
|
3.
Tigon is
generally unfertile. |
3.
Liger is
generally fertile. |
4.
Draw a well
labeled diagram of RNA.
1.
Explain the
structure of RNA.
The ribonucleic acid has all the components same to
that of the DNA with only 2 main differences within it. RNA has the same
nitrogen bases called the adenine, Guanine, Cytosine as that of the DNA except
for the Thymine which is replaced by the uracil. Adenine and uracil are considered
as the major building blocks of RNA and both of them form base-pair with the
help of 2 hydrogen bonds.
RNA resembles a hairpin structure and like the
nucleotides in DNA, nucleotides are formed in this ribonucleic material(RNA).
Nucleosides are nothing but the phosphate groups which sometimes also helps in
the production of nucleotides in the DNA.
2.
"Male is
responsible for the sex determination of an offspring." Justify this
statement.
Females have two
sex chromosomes known as “XX” or the homogametic sex whilemales have two sex
chromosomes too, but they are different than that of the female: They are the
“XY” chromosomes, also known as the heterogametic sex.
A baby gets
chromosomes from both the mother and father. The mother always gives the X sex
chromosome, because she has only x. The father, however, can give either an X
or a Y.
During the
sexual intercourse, if the sperm containing X chromosome fuses with ovum, the
sex of the child will be female (XX) and if the sperm containing Y chromosome
fuses with ovum, the child will be a male child (XY). Hence we can say that
male is responsible for the sex determination of an offspring.
3.
How is sex
determined in human beings?
In human being,
male is heterogamy, so a male produces two types of gametes containing either X
chromosome or Y chromosome. The female is homogamy and hence she produces one
one type of gamete containing X chromosome only. The sex of a child is
determined on the basis of the fusion of the gametes of male, whether it
contains X chromosome of Y chromosome.
4.
Draw a chart to
show the type of offspring produced in F1 and F2 generations after the cross
fertilization between a tall pea plant (TT) and dwarf pea plant (tt). Write the
phenotype and genotype ratio.
Let us consider
Pure tall plant with trait TT as dominant and pure dwarf plant with traits tt
as recessive. When a pure tall plant (TT) is cross pollinated with pure dwarf
(tt), all the progeny obtained are phenotype tall and genotype hybrid tall in
the first filial (F1) generation. When the seeds obtained from F1
generation are sown and allowed to self-pollinate and seeds collected are sown,
the phenotype ratio of tall and dwarf is 3:1 while the genotype ratio of pure
tall: hybrid tall: pure dwarf is 1:2:1. This can be elaborated in the figure
below.
Result of F1
Generation by cross-pollination:
Phenotype: All
tall
Genotype: All
hybrid Tall (Tt)
Result of F2
generation by self-pollination:
Phenotype: Tall:
Dwarf; 3:1
Genotype: Pure
tall: hybrid tall: pure dwarf; 1:2:1
1.
When a cross is
made between Pure Red flowered pea plant with a pure white flowered pea plant,
all the progeny obtained in F1 generation are red. No white progeny was
observed. But when self pollination is done between the progeny obtained in F1
generation, white flowered pea plants are seen in F2 generation. Give reason
with explanation.
As we know that
red flower is a dominant character and white flower is a recessive character.
The gene representing dominant character is RR and the gene representing
recessive character is rr. According to the Mendel's law of dominance, when a
cross is made between pure red flowered pea plant and pure white flowered pea
plant, all the progeny obtained in F1 generation are red flowered
phenotypically. None of the progeny of F1 generation is white flowered. This is
because the red flowered (RR) character is dominant over white flowered (rr)
character. The expression of white flower is not possible until there is Red
character. Though white character remains there in a hybrid red plant, it
remains hidden. z€
2.
Make a chart for
the cross between a white colour skinned and black colour skinned human up to
F2 generation.
Let us consider
that the alleles of Pure black skinned man is BB and it is a dominant character
while pure white colour skinned women alleles are denoted by bb, which is a
recessive character.
The cross
between them for the first generation is
shown in the table below.
|
male Female |
B |
B |
|
b |
Bb |
Bb |
|
b |
Bb |
Bb |
In the first
filial generation, all the progeny are phenotypically black but genotypically
hybrid black. When the progeny of first filial generation are allowed to breed
among themselves, the result obtained is shown in the checker board below.
|
male Female |
B |
b |
|
B |
BB |
Bb |
|
b |
Bb |
bb |
The result
obtained in Second Filial generation is given below:
Phenotype ratio:
Black : white; 3:1
Genotype ratio:
Pure black : hybrid black : pure white ; 1:2:1
3.
Mention some
uses of genetic technology.
Genetic
technology has a wide range of uses.
iii) It can also be used to cure genetic
conditions.
4.
Write the
advantages of genetic technology.
Advantages of
genetic technologyare as follows:
a)
Gene therapy:
Genetic technology can be used to diagnose and treat genetic diseases such as
cystic fibrosis, sickle cell anemia, and haemophilia.
b)
Agriculture and
Food Production: Genetic technology can be used to produce varieties of food
and vegetables with high nutrition, more resistivity and high yielding
capacity.
c)
Environmental
Protection: Genetic technology can be used to develop organisms that can
degrade pollutants such as plastic and toxins in the environment, clean up oil
spills, and improve soil quality.
d)
Forensic
Science: Genetic technology can be used in forensic science to identify
individuals and solve crimes.
e)
Evolutionary
Biology and Biodiversity Conservation: Genetic technology can be used to study
evolutionary relationships between species and understand biodiversity
patterns. It can also help identify endangered species and develop conservation
strategies.
Glossary:
|
Genetics: |
the study of
how, in all living things,
the characteristics and qualities of parents are
given to their children by
their genes. |
|
Heredity: |
Process of transmission of parental character from
parents to their offspring. |
|
Variation: |
An individual that possesses characteristics
different from the others of the same kind. |
|
Dominant : |
The character that expresses itself by suppressing
the other character |
|
Recessive: |
The character which fails to get expressed in
first filial generation and usually hidden. |
|
Allele |
An alternative form of matching gene (Tt) |
|
Hybrid: |
An offspring of genetically dissimilar parents or
stocks. |
|
Monohybrid: |
The cross involving one pair of contrasting
character. |
|
Dihybrid: |
The cross involving two pairs of contrasting
character. |
|
Segregation: |
The separation of pair of alleles or homologous
chromosomes. |
|
Filial: |
Generation |
|
Sire: |
A male parent of an animal |
|
Dam: |
A female parent of an animal. |
|
Forensic: |
The use of science and technology in the
investigation and establishment of facts. |
|
Cross-breeding: |
The process of crossing one species with another.
Such as lion+tiger=Liger |
|
Insemination: |
To inject or introduce semen in the reproductive
tract of female. |
|
Surrogacy: |
The process of hiring a female for the production
of offspring. |
|
Heterosis: |
Increase in growth, size and other characteristics
of hybrid. |
|
Inbreeding: |
The breeding or mating of closely related
individuals. |
|
Hybridization: |
The process of producing hybrid. |
|
Outbreeding: |
The breeding or mating of unrelated species. |
|
Inheritance: |
The process of transmission of genetic character
from parents to offspring. |
|
Cell: |
The fundamental, structural and functional unit of
life. |
|
Cell division: |
The biological process through which a
pre-existing diploid cell divides into two or four daughter cells. |
|
Mitosis: |
An equational cell division of a diploid mother
cell into two diploid daughter cells. |
|
Meiosis: |
The reductional cell division of a diploid cell
into two haploid daughter cells. |
|
DNA: |
Abbreviation of Deoxyribonucleic acid is a genetic
material that is responsible for the transmission of genetic information from
one generation to another. |
|
RNA: |
Ribonucleic acid is a single stranded macromolecule
helps in protein synthesis. |
|
Chromosomes: |
The thread like microscopic structures made up of
histone protein and DNA present in the nucleus of a cell are called
chromosome. |
|
Chromatids: |
The two identical thread like strands of a
longitudinally split chrosome are called chromatid. |
|
Centromere: |
The chromatids are connected at the center by a
spherical body called centromere. |
|
Autosome: |
The chromosomes which determine somatic body
structure. |
|
Sex chromosome: |
The chromosome which determine sex of the offspring. |
|
Gametes: |
The haploid cell which take part in sexual
reproduction. |
|
Sex determination: |
The biological cause for an organism developing
into one sex or other due to the genes present in the fused gametes. |
|
Gene: |
The smallest hereditary unit present in
chromosome. |
|
DNA testing: |
The technology which helps to count the number of
chromosomes and identify the change in genes, chromosomes and genomes is
called DNA testing. |
|
Diploid cell: |
A cell having 2n Chromosome. |
|
Haploid cell: |
A cell having n chromosome. |
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