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Answer is (B) Only Tt

Answer is (D) 5643

The process of evolution through which new species are going to be formed is known as speciation or macro evolution.

A) The process of species formation

B) Homologous organs

August Weismann, tested the theory proposed by Lamarck by experiments on rats. He removed tails of parental rats. He observed for twenty two generations but still off springs are normal with tails.

The allosome in males is XY

Chromosomes whose number and morophology do not differ between males and females of a species are called autosomes.

(B) 22 pairs

Autosomes: An autosome is any chromosome that is not a sex-determining chromosome. In humans, there are 22 Pairs of autosomes.

Allele: It is an alternative form of a gene that is located at a specific position on a specific chromosome.

(B) Law of Segregation

Characters from your parents and grandparents is by genes

(A) Homologous organs

(B) Wings of Bat

Answer is (C) Yy-Rr

The organisms which have the patagium (skin folds) is Bat

(D) Colour of root

Correctly matched column:

Correct option is: (a) Haemophilia

Correctly matched column:

• Sickle-cell anaemia is a hereditary disease caused due to mutation of a single gene. 
• It is a monogenic disorder that occurs due to changes in a gene during conception.
• If father and mother both are sufferers or carriers of sickle-cell anaemia, their offsprings are likely to suffer from the disease.
• Therefore, a carrier or sufferer of sickle-cell anaemia should avoid marriage with another carrier or sufferer.

• Phenotype means external appearance or visible characteristics of organisms whereas the genotype is the pairs of genes responsible for the visible characteristics.
• The genes responsible for any particular character are present in pairs.
• Though, there are two genes, the phenotype depends on the presence of the dominant gene, e.g. Genotype for tall height of the plant is TT or Tt.
• Therefore, phenotypic and genotypic ratios are different.

(a) Round-Yellow: 9 

(b) Wrinkled-Yellow: 3 

(c) Round-Green: 3 

(d) Wrinkled-Green: 1 

Phenotypic ratio: 9:3:3:1

• Tobacco smoke contains harmful chemicals like pyridine, ammonia, aldehyde furfural, carbon monoxide, nicotine, sulphur dioxide etc. 
• They cause uncontrolled cell division. 
• Tobacco smoke is full of minute carbon particles which cause normal tissue lining of the lung to transform into thickened black tissue. This leads to cancer. 
• Therefore, tobacco smoking causes cancer.

(a) RRYY -1 

(b) RRYy-2 

(c) RRyy-1 

(d) RrYY-2 

(e) RrYy-4 

(f) Rryy-2 

(g) rrYY – 1 

(h) rrYy – 2 

(i) rryy – 1 

Genotypic ratio: 1:2:1:2:4:2:1:2:1

• Smoking of cigarettes and bidis adversely affects the process of digestion. 
• It causes a burning sensation in the throat and cough. 
• Excessive smoking causes instability and trembling of fingers. 
• It causes dry cough which leads to sleeplessness. 
• Tobacco consumption can lead to shortening of life span, chronic bronchitis, pericarditis, cancer of the lungs, mouth, larynx (voice box), pharynx, urinary bladder, lips or tongue. 
• The nicotine present in tobacco affects the central and peripheral nervous system. Arteries become hard i.e. it causes arteriosclerosis and hypertension.

Table for number of chromosomes in different organisms.

Alfred Russel Wallace concluded that natural selection contributed to the origin of new species.

• Klinefelter syndrome is a disorder arising in men due to abnormalities in sex chromosomes.
• In this disorder, men have one extra X chromosome, hence their chromosomal condition becomes 44 + XXY.
• Such men are usually sterile because their reproductive organs are not well developed.

• Down syndrome is the disorder arising due to chromosomal abnormality. 
• This is the first discovered and described the chromosomal disorder in human beings.
• This disorder is characterized by the presence of 47 chromosomes. It is described as the trisomy of the 21^st pair.
• Infants with this disorder have one extra chromosome with the 21^st pair in every cell of the body. Therefore, they have 47 chromosomes instead of 46.
• Children suffering from Down syndrome are usually mentally retarded and have a short lifespan. Mental retardation is the most prominent characteristic.
• Other symptoms include short height, short wide neck, flat nose, short fingers, scanty hair, single horizontal crease on palm and a life expectancy of about 16-20 years.

Correct answer is:

a. Klinefelter syndrome 

b. Dihybrid 

c. Klinefelter syndrome

A) homologous organs

(C) Galapagos islands

1. Adenine. It is a purine whereas the others are pyrimidines.

2. Green seed. It is a recessive character of pea plant whereas the others are dominant characters.

3. Constricted pod. It is a recessive character of pea plant whereas the others are dominant characters.

4. Green pod. It is a dominant character of pea plant whereas the others are recessive characters.

5. Presence of hair on arms. It is a dominant characteristic of human beings whereas the others are recessive characters.

6. Spina bifida. It is a polygenic disorder whereas the others are monogenic disorders.

7. Leber hereditary optic neuropathy. It is a mitochondrial disorder whereas the others are monogenic disorders.

Correct option is: (a) Absence of hair on arms

Correct option is: (d) Free ear lobe

Correct option is: (c) Yellow colour of seeds

1. During the course of evolution some organs remain in organisms, even though they don’t have any work to do. 

2. For example appendix in the digestive system of human beings has no role to play in the process of digestion.

3. But in herbivores like rabbit appendix plays important role. 

4. Such type of organs which are not useful in animal are called “vestigial organs”.

5. There are nearly 180 vestigial organs in human beings such as pinna, hair on skin, mammary glands in human, etc. 

6. That’s why human being is said to be a moving museum of vestigial organs.

Number of vestigial organs present in human beings is 180

The appearance of vestigial organs in human beings is called Atavism

1. Ancient human beings travelled from one place to other in search of better living conditions such as availability of food, water shelter and other facilities. 

2. They did not travel in a single line.

3. They went forwards and backwards with groups, sometimes separating from each other. 

4. This travel is responsible for the formation of races.

1. Carbon dating is the method used to calculate the age of rocks, minerals or fossils. 

2. The breakdown of radioactive isotopes of certain elements such as carbon, uranium and potassium takes place at a known rate. So the age of rock or mineral containing isotopes can be calculated. 

3. Archaeologists use the exponential, radioactive decay of carbon 14 to estimate the death dates of organic material. 

4. The earth’s atmosphere contains various isotopes of carbon, roughly in constant proportions. 

5. These include the main stable isotope¹²C and an unstable isotope¹⁴C. 

6. Through photosynthesis, plants absorb both forms from carbon dioxide in the atmosphere.

7. When an organism dies, it contains the standard ratio of ¹⁴C to ¹²C. 

8. But as the ¹⁴C decays with no possibility of replenishment, the proportion of carbon 14 decreases at a known constant rate. 

9. The time taken for it to reduce by half is known as the half-life of ¹⁴C, which is 5730. 

10. The measurement of the remaining proportion of ¹⁴C in organic matter thus an estimation of its age. 

11. As the half life of carbon – 14 is 5,700 years, it is useful for dating objects up (o about 60,000 years old.

1. Deer that can run fast can survive in the forest. Because they can escape easily from lions and tigers, when compared to second type. 

2. Deer that run slowly are going to be eliminated. Because they can be caught easily by its predators. So the survival chance will decrease.

The characters developed during the lifetime of an organism are called acquired characters.

1. No, there is no biological basis to the notion of human races. All humans are a singlespecies. 

2. Regardless of where we have lived for the past few thousand years, we all came from Africa. 

3. The earliest members of human species, Homosapiens, can be traced there. 

4. Our genetic footprints can be traced back to our African roots. 

5. A couple of hundred thousand years ago, some of our ancestors left Africa while others stayed on. 

6. While the residents spread across Africa, the migrants slowly spread across the planet. 

7. They did not go in a single line. They went forwards and backwards, with groups, sometimes separating from each other, even moving in and out of Africa. 

8. Like all other species on planet, they had come into being as an accident of evolution,and were trying to live their lives the best they could.

D) Survival of the fittest

1. The given information gives the evidences of evolution. 

2. Mammals. birds, reptiles and amphibians all these have forelimbs which have similar basic structure. 

3. But they are modified to perform different functions. 

4. This indicates that all the vertebrates have evolved from a common ancestor. These organs are called homologous organs. This type of evolution is called divergent evolution. 

5. In case of bat (mammal) and bird the designs of the two wings, their structure and components are different.

6. They look similar because they have common use for flying, but their origins are not common. 

7. These organs which are structurally different but functionally similar are known as ‘Analogous organs’. This type of evolution is called “convergent evolution”. 

8. There are remarkable similarities in the embryos of above mentioned animals even in their limb formation. These are called embryological evidences.