Chapter-21
Heredity
Learning Card-1
Choose the correct answer:1. The ratio of plants obtained in dihybrid cross experiment is
a) 3:1 b) 9:1:3:1 c) 3:1:9:1 d) 9:3:3:1
2. The Genetist who conducted hybridization experiments on four “o” clock plant is.
a) Carlcarrens b) Mendel c) mendeleeve d) Darwin
3. The Scientist who developed first cloned sheep is
a) Johnson b) Carl Correns. c) Mendel d) wilmut
Answer the following questions:
4. What is genetics?
Genetics is a branch of biology which deals with a systematic study of Heredity, variations and factors responsible for these.
5. Who is the father of modern genetics?
Gregor Johann Mendel.
6. What is monohybrid cross?
A Cross between two pea plants which differ in one specific character is called monohybrid cross.
7. What is dihybrid cross?
A cross between two pea plants which differ in two pairs of contrasting characters is called dihybrid cross.
8. What is DNA replication?
During the interphase before the cell divides DNA found in every chromosome, replicates to ensure equal distribution of the genetic material to the future daughter cells. This process is called DNA replication.
9. Define Biotechnology.
The application of technological procedures on organisms or their process or their products to obtain new substances for human welfare is called Biotechnology.
10. What is genetic engineering?
Genetic engineering is the technique of inducing desirable changes in the gentic material such as DNA of an Organism
11. What is cloning?
Cloning is the technique of developing genetically similar molecules, cells, tissues or organism from a common precursor in vitro laboratory condition.
12. What is heredity?
Heredity is the inheritance of parental characters by their off springs.
13. Define a) Law of segregation b) Law of independent assortment
a) The Pair of factors for a given character separates in equal ratio at the time of gamete formation during meiosis. It means that a gamete can carry a factor responsible for only one form of a character
b) Factors controlling separate characters normally move independent of each other during gamete formation. So combinations. Of characters which are not present in the parental forms are produced in the next generation
14. What are genes? Who introduced this for the first time?
A part of DNA which gives instructions for making a given kind of protein is called a gene genes help in the inheritance of characters from parents to children.
Johnson introduced the term genes for the first time.
Chapter-21
Heredity
Learning Card-2
Choose the correct answer:1. In DNA molecule adenine combines with the nitrogen base called.
a) Cytosine b) Thymine c) Guanine d) Glucagon.
2. The technology used to transfer nitrogen fixing gene from bacteria into plants is called.
a) Genetic engineering b) DNA recombinant technology
c) DNA finger print technology d) Tissue culture.
Answer the following questions:
1. What is Heredity?
The inheritance of parental characters by their off springs is called Heredity.
2. What are the reasons for Mendel to select pea plant for his experiments?
* They can be grown easily in open ground or even in pots.
* They have a short growth period and life cycle.
* They give self pollinating flowers and also it is easy to conduct cross pollination artificially.
* They produce large number of seeds.
* They show contrasting heritable characters.
3. With the help of a checker board write the ratio of monohbrid cross.
4. Name the two types of mendels laws of heredity.
* law of segregation.
* law of independent assortment.
5. What is incomplete dominance? Explain this with illustration.
In a few plants the results of monohybrid and dihybrid crosses could not be interpreted in terms of Mendel’s principles. They showed many deviations from Mendelian inheritance. This is called “Incomplete dominance”
Eg: Hybridization experiment on ‘Four o clock plant’. In these plants when pure red flower plants are cross breeded with pure white flower plants in the F1 generation pink flowers are formed.
6. What is the difference between DNA and RNA?
DNA has deoxy ribose sugar where as RNA has only ribose sugar.
7. What is complementary base pairing?
Adenine Pairs with Thymine and Guanine Pairs with cytosine. This is called complimentary base pairing.
8. Mention the importances of DNA.
* A DNA has the coded information for controlling all the metabolic activities of the cell both directly and indirectly.
* By its special property of self replication, it ensures the equal distribution of similar genetic material to off springs and thus responsible for heredity.
* DNA synthesises RNA which codes for the synthesis of specific proteins. So DNA indirectly helps in proteins synthesis.
* DNA sometimes undergoes mutation and recombination which bring about variations in the characters of the off spring.
9. What is DNA recombinant technology? What are its advantages?
It is the technique of manipulating genes in the laboratory.
It is possible now with this technique to separate the desirable or useful gene from a cell and introduce it into another cell where it is made to express.
10. What is DNA finger print technology? Name the field in which this technology is used.
The technique involving the breaking down the DNA of an individual into short segments using specific enzymes, then separating the same using a process called gel electropharesis is called DNA Finger print technology.
This technology is used in field of Forenisc science.
11. Mention the applications of biotechnology.
* Large scale synthesis of life saving drugs like antibiotics, vaccines, artifical harmones etc.,
* Improvement of plant and animal breeds, pest and pathogen control in agriculture.
* Synthesis of acceptable additives in food processing and management industries.
* Synthesis of biocatalysts and biopolymers.
* Pollution control: Sweage treatment or water recycling.
12. What are the limitations of biotechnology?
* Seed sterility in plants.
* cloning would pose very serious social, ethical moral and cultural problem.
* Genetically modified foods have started threatening the human and animal health.
* It would upset the delicate balance of the nature.
Chapter-21
Heredity
Learning Card-3
Answer the following questions:1. Make a list of any four observable traits in pea plants with their contrasting forms of characters.
2. State the principle of dominance with an illustration.
When two factors are responsible for a pair of contrasting forms of a single character, come together, normally one expresses itself while the other does not. For any given character, there are two forms of factors. One factor is dominant and the other is recessive. This idea is known as the principal of dominance.
3. Which are the four types of pea plants did Mendel get in the dihybrid cross experiment?
With the help of a checker board write the ratio.
Dihybride ratio 9:3:3:1
4. What is the difference between phenotype and genotype?
Phenotype is theration of number of plants obtained in F1 generation.
Genotype is the ratio of number of pure plants and mixed plants, in F2 generation.
5. Heredity variations are very important. Give reasons.
Heredity variations are very important because they show the differences between father, mother and children. This is useful in inheritance of characterstic features inb generation.
6. Explain the structure of DNA as per Watson and Krick.
DNA is the genetic material which carries genetic information from one generation to the other.
The sturcture of DNA molecule remembles a spirally twisted ladder. It is called as double helix. The molecule of DNA has a pair of polynucleotide chains running antiparallel to each other. They are interwined and each chain is helically coiled around the other. Each polynucleotide chain has a series of nucleotide units. Each nucleotide unit consisits of three components namely
1) Deoxyribose Sugar 2) Phosphate and 3) Nitrogen base.
The nitrogen bases connect the two opposite strands like the rungs of a ladder. The nitrogen bases are adenine, Guanine, Thymine and cytosine.
7. Although biotechnology appears to be a boon for mankind. In future it may be the cause for serious Problem. Give reasons.
· It causes sterility of seeds in plants.
· Cloning would pase very serious social, ethical, moral and cultural problem.
· Possibilities of using this techniques for illegal purpose and destructive activities.
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