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Following are the special features of the power – separation theory: 

1. Decentralization of power: 

The power – separation theory divides the administration into three organs: 

• the legislature 
• the executive 
• the judiciary.

By division of work and power, the government works more smoothly, more efficiently and more speedily, and this also discourages corruption and tyranny.

2. Protection of citizens’ freedom: 

The power – separation theory discourages the arbitrator and despotic tendency of governance, and protects individual freedom. No organ of the government can hinder the citizens’ freedom. 

3. Check on despotic administration: 

he greatest advantage of power – separation theory is that despotic rule cannot be established.

Need for power – separation theory: 

Following are the causes for the need of power separation theory: 

1. To prevent the administration from becoming autocratic 

2. To ascertain the responsibilities of the different organs of the administration 

3. To protect the freedom and rights of the people 

4. To increase the efficiency of administration 

5. To check the misuse of political powers 

6. To maintain the freedom and impartiality of judiciary, power – separation theory is essential 

7. To enable monitoring of one power by another power 

8. To prevent the concentration of power, and thereby the autocracy of the government.

The power of bringing a resolution of impeachment.

The principle of checks and balances means that all the three organs of the government must act in such harmony and co – ordination that all the three organs should keep a check on one another that none can develop a tendency of despotism and all the powers of the three organs can give maximum benefit of administration to the people.

Aim of this principle – 

The legislature, the executive and the judiciary have to work within the constitutional dignity and not to create an adverse effect on the administration. According to the theory of checks and balances, the powers of the three organs of the states so manage the administration of the state that they may work in their functional areas independent of others and should exercise mutual control, so that there should be a good balance among the three organs.

By doing so, all the three organs of the state are balanced in their performance and achievement. The mutual control on one another keeps them in balance and does not let them turn despotic in duty and behaviour. The result is that none of the three organs can misuse its power. Thus, they maintain a balance among the three power of administration.

By doing so, all the three organs of the state are balanced in their performance and achievement. The mutual control on one another keeps them in balance and does not let them turn despotic in duty and behaviour. The result is that none of the three organs can misuse its power. Thus, they maintain a balance among the three power of administration.

In U.S.A., the Supreme Court has almost all legal powers, yet, the President and the Congress exercise a considerable influence over it. The Congress can remove the judges from their office through impeachment and can limit the functional area of the Supreme Court. The Congress can increase the number of the judges.

The Congress, by law, decides the terms and conditions of the judges’ term. It also decides their salaries and other facilities. The President appoints the judges and has a right to grant pardon to a criminal. Besides, whatever law is made by the legislature, its approval has to be taken from the President.

In U.S.A. all the the law – making powers have been given to the Congress. However, the President and the judiciary have been empowered through checks and balances to control the despotic tendency in the Congress. The President has a right to opine on the law – making agenda of the Congress and can send his clear message to the Congress.

The Congress, after passing a bill, will send it to the President for his approval. Then and then alone it can become a law fit to be enforced. Regarding the approval, the President has veto power to reject any bill sent for approval without assigning any reason. The Supreme Court, through its power of judicial review, can reject any law.

The correct answer is A) Tendon.

A – 4 

B – 3

C – 2

D – 1

India has been divided into very high risk earthquake zone, high risk earthquake zone, medium risk earthquake zone, low risk earthquake zone and very low risk earthquake zone.

There are least earthquakes in the region of Southern Plateau as it is a fixed land part.

Correct Answer is: (c) 77 districts

DNA ligase enzyme that joins the small fragments of DNA of a lagging strand during DNA replication.

The two strands of RNA (i.e. sense and antisense) being complementary will bind with each other and form double stranded RNA. As a result its translation and protein expression would be inhibited. 

They (worked on the bio-chemical nature of transforming principle in Griffith's experiment) purified proteins DNA and RNA from heat killed S cells, they discovered protein digesting enzyme (protease) RNA digesting enzyme (RNese) did not affect transformation, Digestion with DNase inhibited transformation, concluded DNA is the heredity material.

Detailed Answer :

Oswald Avery, Colin Macleod and McCarty worked to determine the biochemical nature of 'transforming principle' in Griffith's experiment. They purified biochemicals (proteins, DNA, RNA etc.) from the heat killed S cells to see,which ones could transform live R cells into S cells.

They discovered that :

(i) Digestion of protein and RNA (using Proteases and RNases) did not affect transformation. So the transforming substance was not a protein or RNA.

(ii) Digestion of RNA with DNase inhibited transformation. It means that DNA caused transformation of R cells to S cells, i.e. DNA was the transforming substance. Therefore they concluded that DNA is the hereditary material.

(1) Nucleotides of DNA contain deoxyribose pentose sugar and the nitrogenous bases adenine / guanine / cytocine / thymine, while in the nucleotides of RNA the pentose sugar is ribose and the nitrogen bases similar to those of DNA except that there is uracil in place of thymine. 

(2) RNA may function as messenger (mRNA) adapter (t RNA), structural (rRNA) molecule. In some cases it may perform catalytic functions. 

(3) DNA acts as a most suitable genetic material because of the following reasons : 

(i) It is structurally most stable and is less reactive. 

(ii) It is capable to replicate itself. 

(iii) It express itself in the form of Mendelian traits. 

(iv) The teacher has a scientific attitude, love for his students and has the ability to express even the difficult subject matter in a simple way which is easily understood by the students.

Streptococcus pneumonia

S - Strain 'inject into mice' mice die. 

R - strain 'inject into mice' mice alive. 

S - strain (heat killed) 'inject into mice' mice alive. 

R - strain (alive) + S (heat killed) strain'inject into mice' mice die. 

R strain transformed into virulent.

Detailed answer:

Transforming Principle:

Frederick Griffith (1928) conducted experiments with Streptococcus pneumoniae ( bacterium causing pneumonia).

(i) He observed two strains of this bacterium-one forming smooth shiny colonies (S-type) with capsule, while other forming rough colonies (R-type) without capsule. 

(ii) Capsulated S-strain was virulent and causes pneumonia whereas non capsulated R-strain was not virulent and does not cause pneumonia. 

(iii) When live S-type cells were injected into mice, they died due to pneumonia. 

(iv) When live R-type cells were injected into mice, they survived 

(v) When heat-killed S-type cells were injected into mice, they survived and there were no symptoms of pneumonia.

(vi) When heat-killed S-type cells were mixed with live R-type cells and injected into mice, they died due to unexpected symptoms of pneumonia. 

(vii) He concluded that heat-killed S-type bacteria caused a transformation of the R-type bacteria into S-type bacteria but he was not able to understand the cause of this bacterial transformation.

(1) The students carried on the experiment performed by Avery, Macleod and McCarty in 1944, who investigated the biochemical nature of transforming principle in Griffith's experiment. 

(2) Frederick Griffith performed the transformation experiment in 1928. 

(3) Refer to quick review on page 135. 

(4) Scientific attitude, awareness and respect to their teacher.

Purified biochemicals (protein, DNA, RNA) from heat killed S - strain. 

Treated with protease - did not affect transformation. 

Treated with RNase - did not affect transformation. 

Treated with DNase - transformation affected.

Detailed answer:

Chemical nature of transforming principle was established by Avery, Macleod and mccarty. They purified the biochemical (proteins, DNA, RNA etc) isolated from heat killed S-cells. They discovered (a) That digestion of protein and RNA, using the enzymes proteases and RNases did not affect transformation. So the transforming principle was not protein and RNA. (b) While digestion of DNA with DNase inhibited transformation. On this basis they concluded that DNA caused transformation of R-cells to S-cells, i.e., DNA was the transforming principle.

Parthenium or Carrot grass.

The answer is  (D) Rantham bhor

Speciation is the formation of new species from the pre-existing population.
Factors responsible for speciation:
(i) Genetic drift
(ii) Geographical isolation
(iii) Natural selection
(iv) Mutation
Geographical isolation cannot be a major factor in the speciation of a self pollinating plant species because physical barrier cannot be created in self-pollinating plants.

Homologous Organs: Organs with similar basic structure/origin but modified to perform a different function.

Example: Forelimbs of various vertebrates.

Wings of butterfly and the wings of a bat cannot be regarded as homologous organs.

Reasons: Through they perform the similar function they have different origin/basic structure. 

Wings of a bird and wings of a bat are analogous organs as they have different basic structural design but have similar appearance and perform similar functions.

Homologous organs help to identify the relationship between organisms. These characteristics in different organisms would be similar because they have inherited from a common ancestor. For example, forelimbs of human and wings of birds show closeness between the two species because the organs have similar basic structural design of limbs though it has been modified to perform different functions.

Speciation is the evolution of reproductive isolation among once interbreeding population. 

Factors which can lead to speciation are: 

Genetic drift: Over generations, genetic drift may accumulate which leads to speciation. Natural selection: Natural selection may work differently in different location which may give rise to speciation. 

Severe DNA change. A variation may occur which does not allow sexual act between two groups. 

The answer is (a) round and yellow

Round and yellow are the dominant characters hence in f₁ generation all seeds will be  round and yellow.

The answer is (a) reptiles have evolved from birds

• Dinosaurs had feathers but could not fly using them. Birds, later adapted the feathers for flight.
•  Since, dinosaurs were reptiles, this means that birds have evolved from them.

The answer is (a) tallness is the dominant trait

In monohybrid cross only dominant characters are expressed in first progeny

The answer is (d) for every molecule of fat there is a gene

Every, protein enzymes and hormones are controlled by specific gene whereas fats are not controlled by gene hence option d is a wrong statement

The answer is (c) cross fertilisation

• Sex of the individual is determined the genes inherited from the parents. 
• If a newborn acquires X chromosomes from father child will be a female and if newborn receives Y chromosome from father it will be a male

A very small population of a species faces a greater threat of extinction than a larger population because of the following reasons 

Inbreeding

Small population promotes inbreeding. Inbreed results in lesser variations. 

Genetic drift

Small population is vulnerable to sudden change in environment. Because of genetic drift chances of species with small population may wipe out. 

Inbreeding depression 

This lead to negative population growth which is detrimental for the survival of the species with smaller population

• Sex of the offspring is determined by the gamete donated by male. 
• Male possess X and Y chromosomes in their 23rd pair.
• The ration between X and Y is 1. 
• Hence the probability of getting either a male or female child is 50: 50.

• Inspite of the fact that animals have different variety of structures they don not have common ancestry.
• This is because common ancestry may greatly limit the extent of diversity.
• Many of the animals are inhabiting the same habitat, their evolution by geographical isolation and speciation is also not likely. 
• Hence common ancestry for all the animals is not the likely theory.

• Homologous structures are those which has common basic structure and performs different functions. e.g. fore limbs of reptiles, amphibians and mammals. 
• If they don’t have common ancestry they are called as analogous structure

The first step in sexual reproduction is gamete formation. In this step, the number of chromosomes gets halved. Thus, each gamete receives half the number of chromosomes to that of somatic cells. During fertilisation, the fusion of male and female gametes takes place, which results in the number of chromosomes in the zygote to be equal to that of somatic cells. Thus, the chromosomal number of the sexually producing parents and their offspring is the same

Cabbage, Broccoli, Cauliflower, Kohlrabi and Kale.

A trait of an organism which is ‘not inherited’ but develops in response to the environment is called an acquired trait. 

Example – If a beetle does not get sufficient food for a considerable time, its weight will be reduced due to starvation. The low weight of the beetle is an example of acquired trait. A trait of an organism which is caused by a change in its genes (DNA) is called an inherited trait. 

Example – The change of colour from red beetle to green beetle is an example of inherited trait.

RFLP (Restriction Fragment Length Polymorphism): RFLP’s is a molecular method of genetic analysis that allows identification of taxa based on unique patterns of restriction sites in specific regions of DNA. It refers to differences between taxa in restriction sites and therefore the lengths of fragments of DNA following cleavage with restriction enzymes.

Characters transmitted from parents to offspring are present in genes. They are the unit of hereditary.

The answer is (a) they reproduce asexually

Amoeba reproduce by binary fission, Spirogyra reproduce by fragmentation, yeast reproduce by budding.

The answer is (d) genes

Copies of same chromosome from the male and female gametes pair up to form a chromosomal pair or gene which combines the two versions of a trait from both the parents, so as to create a new version of the character in the child.

• Structure which are apparent to our eyes are called morphological structures.
• Molecular structures are those biomolecules which are the integral components of organisms. 
• We see lot of diversity all around us. 
• This diversity is possible because of diversity in morphological structures. 
• This shows that morphological structures are least stable. 
• Life which began as simple forms on the earth in now composed of many complex forms. 
• Life has evolved for millions of years but the structure of basic biomolecules such as DNA remains same. 
• A DNA is same in a human and in a mouse. 
• A protein has same structure in a bird and in a fungi. 
• So, the molecular basis of life has not changed through all these years.
• This proves that evolution has exhibited a greater stability of molecular structure when compared with morphological structure.

The organs of different species, which are similar in function, but have different structural framework are called analogous organs.

For example: wings of a bat, and wings of a bird.

In the F2 progeny, there is one pure tall, one pure dwarf and two mixed tall plants.

The size of an individual’s body depends upon the lifestyle and not much on the genetic constitution. Hence, it is an acquired character.

New species are formed due to change in genetic material of the reproductive tissues of the organism. Thus, changes in the DNA or chromosome number can lead to formation of new species.

Wild cabbage.

The tendril of a pea plant and phylloclade of Opuntia are both stem joints. They have similar basic structure and thus are homologous.