THESE NOTES ARE PREPARED ACCORDING TO JKBOSE SYLLABI IN SIMPLIFIED AND CONCISE PATTERN
Unit Summary:
|
Introduction & Definitions |
Genetics: Study of Heredity and Variation Heredity: Transmission of Characteristics from
one generation of another Variation: Differences in the traits among the
individuals in a population Natural Selection: The survival of organism with
good variations in the environment |
|
Traits |
Inherited Traits: Those traits that are passed on from
one generation to another. Acquired Traits: Those traits that are acquired from
the environment. |
|
Mendel (1822-84) & his experiments with Pea Plant
(Pisum Sativum) |
Considered as Father of Genetics. Conducted experiments on Pea plant and Hawkweed. Selected 7 contrasting traits in Pea plant and
performed cross hybridization between two pure varieties such as (Tall/Short
Plant) (Yellow/White flowers) (Round/Wrinkled Seeds) (Green/ Yellow Pod) etc. Performed Monohybrid and Dihybrid Crosses |
|
Mendel’s Laws |
Law of Dominance: When two contrasting traits
are crossed, one trait is dominant over the other. Law of Segregation: Two alleles of a trait segregate
during the formation of gametes and offspring acquires one allele from each
parent Law of Independent Assortment: The alleles for
different characteristics pass into gametes independently of each other and
do not affect each other. |
|
Mendelian Ratio’s |
MonoHybrid Cross: Phenotypic ratio: 3:1 Genotypic Ratio: 1:2:1 Dihybrid Cross: Phenotypic ratio: 9:3:3:1 Genotypic Ratio: 1:2:1:2:4:2:1:2:1 |
|
Phenotype and Genotype |
Phenotype: The traits that are observable in the body
of an organism Genotype: The traits that are not observable in the
body of an organisms but are hidden in its genes. |
|
DNA (Deoxy Ribose Nucleic Acid) |
DNA: Genetic material of the cell. It is double
helix which contains Nitrogen base, Ribose sugar and Phosphate group. DNA forms RNA which forms Proteins. Proteins perform
various functions in body |
|
Sex Determination in Humans |
Humans have sex chromosomes. XX in females and XY in
males. If Sperm with X chromosome fertilizes egg, the offspring
is Female If sperm with Y chromosome fertilizes egg, the
offspring is Male |
|
Factors that affect Evolution |
Natural Selection > Genetic Drift > Mutations
> |
|
Homologous organs |
Organs in different organisms that have same structure but
different function e.g. Forelimbs of Human, Bird, Bat, Whale |
|
Analogous Organs |
Organs in different organisms that have different
structure but perform same function e.g. Wings of Insects and Wings of Birds |
|
Vestigial Organs |
Rudimentary organs that were useful to the ancestors of
a population but do not any function now. e.g. Vermiform Appendix, Tail bone,
Wisdom teeth in humans |
Textual Questions
Q. If a trait A exists in 10% of population of an asexually reproducing species and trait B exists in 60% of same population, which trait is likely to have arisen earlier?
Ans: The trait B exists in more population than trait A. Therefore it is likely to have arisen earlier.
Q. How does the creation of variation in a species promote survival?
Ans: Variation arises due to changes in DNA. It helps the species to adopt to environmental changes.
It helps in survival of organisms.
Q. How do mendals experiments show that gene may be dominant or recessive?
Or
Discuss Law of dominance?
Q. If a trait A exists in 10% of population of an asexually reproducing species and trait B exists in 60% of same population, which trait is likely to have arisen earlier?
Ans: The trait B exists in more population than trait A. Therefore it is likely to have arisen earlier.
Q. How does the creation of variation in a species promote survival?
Ans: Variation arises due to changes in DNA. It helps the species to adopt to environmental changes.
It helps in survival of organisms.
Q. How do mendals experiments show that gene may be dominant or recessive?
Or
Discuss Law of dominance?
Or
How do Mendel’s experiment show that traits may be dominant or recessive?
Ans: Mendal did an experiment on Pea plants to show that gene/trait may be dominant or recessive.
He crossed Pure Tall plant (TT) with Pure Dwarf plant (tt). The plants produced were Tall (Tt).
This generation was called F1 generation.
When he crossed the plants of F1 generation among themselves, both tall and short plants produced were in the ratio of 3:1.
This showed the gene of tallness was dominant over gene of shortness.
Q. How do Mendals experiments proved that traits are inherited independently?
Or
Discuss Mendals law of Independent Assortment?
Ans: Mendal proved that traits are inherited independently on basis of dihybrid cross.
He selected dominant Plant with Round and Yellow seeds (RRYY) and recessive plant with Wrinkled Green Seeds (rryy) .
The F1 generation had Round and Yellow seeds (RrYy).
Upon selfing the F1 generation, two new recombinant forms were produced besides two parental forms in the ratio of 9:3:3:1.
It showed the genes assort independently of each other.
Q. A man with blood group A married a person with blood group O. Their daughter has blood group O. Is this information enough to tell you the blood group trait A or O is dominant. Why or why not?
Ans: The information is not sufficient to determine if blood group A or O is dominant.
This is because Blood group A can be genotypically AA of AO.
Q. How is sex of the child in human beings determined in human beings?
Ans: The Sex of child is determined by sex chromosomes. Humans have 46 chromosomes.
44 chromosomes are autosomes whereas 2 chromosomes are Sex chromosomes.
Males have X and Y sex chromosomes where as females have X and X chromosomes.
When the sperm containing X chromosome of males fertilizes the egg of female, the sex of offspring will be female (XX)
When the sperm containing Y chromosome of male fertilizes the egg of female, the sex of offspring will be male (XY).
Ans: Mendal did an experiment on Pea plants to show that gene/trait may be dominant or recessive.
He crossed Pure Tall plant (TT) with Pure Dwarf plant (tt). The plants produced were Tall (Tt).
This generation was called F1 generation.
When he crossed the plants of F1 generation among themselves, both tall and short plants produced were in the ratio of 3:1.
This showed the gene of tallness was dominant over gene of shortness.
Q. How do Mendals experiments proved that traits are inherited independently?
Or
Discuss Mendals law of Independent Assortment?
Ans: Mendal proved that traits are inherited independently on basis of dihybrid cross.
He selected dominant Plant with Round and Yellow seeds (RRYY) and recessive plant with Wrinkled Green Seeds (rryy) .
The F1 generation had Round and Yellow seeds (RrYy).
Upon selfing the F1 generation, two new recombinant forms were produced besides two parental forms in the ratio of 9:3:3:1.
It showed the genes assort independently of each other.
Q. A man with blood group A married a person with blood group O. Their daughter has blood group O. Is this information enough to tell you the blood group trait A or O is dominant. Why or why not?
Ans: The information is not sufficient to determine if blood group A or O is dominant.
This is because Blood group A can be genotypically AA of AO.
Q. How is sex of the child in human beings determined in human beings?
Ans: The Sex of child is determined by sex chromosomes. Humans have 46 chromosomes.
44 chromosomes are autosomes whereas 2 chromosomes are Sex chromosomes.
Males have X and Y sex chromosomes where as females have X and X chromosomes.
When the sperm containing X chromosome of males fertilizes the egg of female, the sex of offspring will be female (XX)
When the sperm containing Y chromosome of male fertilizes the egg of female, the sex of offspring will be male (XY).
Q. What are the different ways in which the individual with a particular trait may increase in a population?
Ans: The different ways in which individuals with a particular trait may increase in population are as under:
1. Reproduction: When individuals of particular trait get more chances of reproduction, their population increases.
2. Natural selection: Nature favours individuals of particular trait to survive and reproduce.
3. Genetic drift: In genetic drift, A section of species dies of natural calamity.
In genetic drift, A trait which is present in less population is likely to perish.
Q. Why are traits acquired during life time of an individual not inherited?
Ans: The acquired traits are not inherited because they don't alter the DNA in germ cells.
Q. Why are the small number of surviving tigers a cause of worry from the point of view of genetics?
Ans: The small number of surviving tigers is a cause of worry due the the fact that there will be very less recombinations and variations. Hence very less useful variations will be produced.
There is a threat of genetic drift as well.
Q. What factors could lead to the rise of new species?
Ans: The factors that could lead to rise of new species are:
1. Isolation: When individuals of particular species are isolated geographically or reproductive. This leads to formation of new species.
2. Mutation: Mutation in genes may lead to formation of new species.
3. Genetic drift.
4. Natural selection.
Q. Will geographical isolation be a major factor in the speciation by self pollinating plant species? Why or why not?
Ans: No because self pollination occurs in flowers of same plant.
Q. Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
Ans: No, geographical isolation will not be a major factor in the speciation of an organism that reproduces asexually.
This is because these organisms involve single parent where replication of DNA occurs. There is no variation as well.
Q. Give an example of characteristic used to determine how close two species are in evolutionary terms?
Ans: Homologous organ can be used to find how close two species are in evolutionary terms. E.g Wings of Bat and Arm of Human have similar structure and show closeness of two species.
Q. Can the wing of butterfly and wing of bird be considered homologous organs? Why or why not?
Ans: No because the wing of butterfly and bird perform same function but have different structure. Therefore they are analogus not homologus.
Q What are fossils? What they tell us about process of evolution?
Or
Q. Explain the importance of fossils in deciding evolutionary relationship?
Ans: Fossils are remains of the organisms that lived in the past.
They help to find evolutionary relation between organisms.
It is proof of fact that complex organisms arose from simple ones.
Q. Why are human beings who look so different from each other in terms of size, colour and looks said to belong to same species?
Ans: A species is group of organisms similar in shape and capable of interbreeding.
Human beings have same shape, they can interbreed and have common ancestor.
The variation in size, colour and looks are due to environment, mutation etc.
Q. In evolutionary terms can we say which among bacteria, spider, fish and chimpanzee have a better body design?
Ans: In evolutionary terms, chimpanzee has more complex body design.
The organism with better body design is one which has survived over long period of time and across different habitats.
Using that criteria bacteria has simple but better body design.
Q. How are areas of study of evolution and classification interlinked?
Ans: Evolution and classification are interlinked.
The classification of organisms is done on basis of its complexity and evolution.
Classification based on evolution has given rise to Phylogenetics.
Q. Explain the terms homologus and analogus organs with examples.
Ans:
Homologus organs: Homologus organs are those organs in different organisms that have same structure but perform different functions.
Examples: Forelimbs of Birds, Mammals, Whales.
Analogus organs: Analogus organs are those organs in different organisms that have different structure but perform same function.
Examples: Wings of insects and birds.
Q. What evidence do we have for the origin of life from inanimate matter?
Ans: The evidence for the origin of life from inanimate matter was given by Urey and Miller.
In an experiment, they mixed molecules like ammonia, methane, hydrogen sulphide and water. This was similar to the atmosphere that existed billions of years ago.
With temperature kept above 100 °C, sparks were passed through the mixture of gases.
When the mixture was analysed, simple compounds of carbon, amino acids etc were found.
Q. Explain how sexual reproduction gives rise to more viable variation than asexual reproduction. How did this affect the evolution of these organisms that reproduce sexually?
Ans: In sexual reproduction, two parents are involved and there is fusion of gamates.
The variations occur due to cross over, recombination, Independent assortment mutation etc.
In asexual reproduction, there is very less variation and offsprings are clones of parents.
So sexual reproduction gives rise to more viable variation than asexual reproduction
Q. How is equal genetic contribution of male and female parents ensured in the progeny?
Ans: Due to meiosis, the haploid set of chromosomes are formed in gamates.
During fertilization, the two haploid set of chromosomes in gamates fuse togather to form diploid organism.
This ensures equal genetic contribution of male and female parents the progeny.
Q. Only variations that confer an advantage to an individual organisms will survive in a population. Do you agree with this statement? Why or why not?
Ans: Yes, The variations that confer an advantage to an individual organism will survive in a population.
Such organisms leave behind more offsprings and will have more variations.
Survival chances also depend on the nature of variations.
Conceptual Questions:
Q. Explain the term variation? What is the importance of variations.
Ans: Genetic variation may be defined as the difference in DNA among a species. The variations occur due to mutation and recombination.
Importance of Variation:
(i) It helps in survival of species.
(ii) It helps organisms to adapt to changes in environment.
(iii) It increases genetic diversity.
(iv) It leads to speciation.
Q. Difference between continuous and discontinuous variations.
Ans:
Q. Difference between acquired traits and inherited traits
Ans:
Ans:
Q. Why did Mendel choose garden pea for his experiments?
Ans: Mendel choose pea plant for his experiments due to following reasons;
i. They are easily available and grows easily.
ii. They complete their life cycle in one season.
iii. They are self pollinating.
iv. They have contrasting traits.
Q. What is gene? What is the nature of Gene.
Ans: Gene is a unit of inheritance which determines the heredity of individual.
Genes are located on chromosomes.
Genes are made of DNA i.e deoxyribose nucleic acid.
Q. Explain Speciation.
Ans: The creation of a new species from an existing one is called speciation.
Speciation brings evolutionary change.
Speciation occurs due to geographical isolation, reproductive isolation, mutations, Genetic drift etc.
Q. What are Vestigial organs?
Ans: Vestigial organs are those organs which are non functional in an organism but were useful to the ancestors of that organism.
E.g Vermiform appendix.
Ans: Mendel choose pea plant for his experiments due to following reasons;
i. They are easily available and grows easily.
ii. They complete their life cycle in one season.
iii. They are self pollinating.
iv. They have contrasting traits.
Q. What is gene? What is the nature of Gene.
Ans: Gene is a unit of inheritance which determines the heredity of individual.
Genes are located on chromosomes.
Genes are made of DNA i.e deoxyribose nucleic acid.
Q. Explain Speciation.
Ans: The creation of a new species from an existing one is called speciation.
Speciation brings evolutionary change.
Speciation occurs due to geographical isolation, reproductive isolation, mutations, Genetic drift etc.
Q. What are Vestigial organs?
Ans: Vestigial organs are those organs which are non functional in an organism but were useful to the ancestors of that organism.
E.g Vermiform appendix.
Q. Give one
example of acquired and inherited trait.
Ans: Acquired
traits include knowledge, skills etc. whereas hereditary qualities include
hair and eye color etc.
Objective Type Questions:
Q. A mendelian experiment consisted of breeding tall pea plants bearing white flowers. The progeny all bore violet flowers , but half of them were short. This suggests that the genetic makeup of tall parents can be depicted as
a. TTWW b. TTww
c. TtWW d. TtWw
Ans: c TtWW
Q. An example of homologus organ is
a. Our arm and dogs fore leg
b. Our teeth and elephants tusk
c. Potato and runners of grass
d. All of above
Ans: All of above
Q. In evolutionary terms, we have more in common with
A. Chinese boy B. Chimp
C. Spider D. Bacteria
Ans: Chinese boy
Q. The tool for tracing evolutionary relationship include:
a. Excavating
b. Time dating and fossils
c. DNA sequencing
d. All of above
Ans: D. All of Above
Q. The amount of DNA in next generation is
A. Double than parents
B. Equal to parents
C. Half than parents
D. Random
Ans: Equal to parents
Q. Which of following in cell nucleus is the information source for making protein?
A. RNA B. DNA C. VACOULE
D. LYSOSOME
Ans: A. RNA
Q. The wings of bird and bat are
A. Homologus but not analogus
B. Neither homologus nor analogus
C. Analogus but not homologus
D. Vestigial
Ans: A. Homologus but not Analogus.
a. TTWW b. TTww
c. TtWW d. TtWw
Ans: c TtWW
Q. An example of homologus organ is
a. Our arm and dogs fore leg
b. Our teeth and elephants tusk
c. Potato and runners of grass
d. All of above
Ans: All of above
Q. In evolutionary terms, we have more in common with
A. Chinese boy B. Chimp
C. Spider D. Bacteria
Ans: Chinese boy
Q. The tool for tracing evolutionary relationship include:
a. Excavating
b. Time dating and fossils
c. DNA sequencing
d. All of above
Ans: D. All of Above
Q. The amount of DNA in next generation is
A. Double than parents
B. Equal to parents
C. Half than parents
D. Random
Ans: Equal to parents
Q. Which of following in cell nucleus is the information source for making protein?
A. RNA B. DNA C. VACOULE
D. LYSOSOME
Ans: A. RNA
Q. The wings of bird and bat are
A. Homologus but not analogus
B. Neither homologus nor analogus
C. Analogus but not homologus
D. Vestigial
Ans: A. Homologus but not Analogus.
Q. The sex of child depends upon chromosome present in:
A. Egg B. Sperm
A. Egg B. Sperm
C. Both Egg and Sperm D. None
Ans: Both egg and sperm.
Q. An organism with two unlike genes of a trait is called:
A. Homozygous B. Heterozygous
C. Hemizygous D. None
Ans: B. Heterozygous
Q. Assertion: Pea plant having violet flowers is crossed with pea plant having white flowers, All the flowers in first generation are violet
Reason: White colour genes are not passed to next generation
Ans: C. A is correct, R is false.
Ans: Both egg and sperm.
Q. An organism with two unlike genes of a trait is called:
A. Homozygous B. Heterozygous
C. Hemizygous D. None
Ans: B. Heterozygous
Q. Assertion: Pea plant having violet flowers is crossed with pea plant having white flowers, All the flowers in first generation are violet
Reason: White colour genes are not passed to next generation
Ans: C. A is correct, R is false.
Q. Assertion: Pea plant is an ideal plant for hybridization experiments.
Reason: Pea plant is easy to grow and has short life cycle.
Ans: Both A and R are true, and R is correct explaination of A.
Reason: Pea plant is easy to grow and has short life cycle.
Ans: Both A and R are true, and R is correct explaination of A.
Q. Assertion: Without variation, evolution is impossible
Reason: Only useful variations are transmitted to next generation.
Ans: A is true but R is false.
Reason: Only useful variations are transmitted to next generation.
Ans: A is true but R is false.
Q. Assertion: Without variation, evolution is impossible
Reason: Only useful variations are transmitted to next generation.
Ans: A is true but R is false.
Reason: Only useful variations are transmitted to next generation.
Ans: A is true but R is false.
Q. Assertion: In a monohybrid cross, Offsprings of F1 generation express dominant characters.
Reason: Dominance occurs only in heterozygous state.
Ans: A is true but R is false.
Reason: Dominance occurs only in heterozygous state.
Ans: A is true but R is false.
Q. Assertion: Without variation, evolution is impossible
Reason: Only useful variations are transmitted to next generation.
Ans: A is true but R is false.
Reason: Only useful variations are transmitted to next generation.
Ans: A is true but R is false.
Reason: Only useful variations are transmitted to the next generation.
(a) Both, A and R, are true and R is the correct explanation of A
(b) Both, A and R, are true but R is not the correct explanation of A
(c) If A is true but R is false
(d) If A is false but R is true
Ans: (d) A is false but R is true
Q. Characters that are transmitted from parents to
offsprings during the sexual reproduction show:
a. Only similarities with parents b. Only variations with parents
c. Both similarities and variations d. Neither similarities nor variations
Ans: c. Both similarities and variations
Q. An example of homologous organ is:
(A) Our arm and a dog's forearm (B) Our teeth arid and
elephant's tusks (C) Potato and runners
of grass (D) All of these
Ans: (D) All of these
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