Human Health and Disease — BIOLOGY STD 12 Science — Question

What is oogenesis? Give a brief account of oogenesis.###Define or Characterise: (i) Primary oocyte. (ii) Primary follicle. (iii) Secondary follicle. (iv) Tertiary follicle. (v) Antrum. (vi) Secondary oocyte. (vii) Graafian follicle.

What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.

Read the following and answer any four questions from (i) to (v) given below:
In recombinant DNA technology, the fragments of DNA generated after cutting the DNA by restriction enzymes are separated according to their size or length by gel electrophoresis. Gel electrophoresis is performed in a gel matrix so that molecules of similar electric charges can be separated on the basis of size. Most commonly used matrix in gel electrophoresis is agarose. The fragments are separated under the influence of electric field. The separated DNA fragments can be seen only after staining the DNA with compound known as ethidium bromide (EtBr) followed by exposure to UV radiation as bright orange band.

1. Gel electrophoresis is used for the separation of

1. DNA only.
2. DNA and RNA only.
3. DNA and proteins only.
4. DNA, RNA and proteins.

2. Most commonly used matrix is _____ which is a ______ extracted from _______.

1. (i) agarose (ii) polysaccharide (iii) sea weed
2. (i) agarose (ii) protein (iii) sea weed
3. (i) EtBr (ii) polysaccharide (iii) sea weed
4. (i) EtBr (ii) protein (iii) bacteria

3. A DNA molecule was treated with a restriction endonuclease and three fragments of size (i) 426kb, (ii) 129kb and (iii) 46kb were obtained. Identify the order in which these bands will arrange themselves in the gel plate after gel electrophoresis is completed. (Assuming that negative part of electrode is towards the well)

1. (iii) → (ii) → (i)
2. (i) → (ii) → (iii)
3. (i) → (iii) → (ii)
4. (iii) → (i) → (ii)

4. Which of the following statements regarding gel electrophoresis is incorrect?

1. Separated DNA fragments can be seen only after staining DNA with EtBr.
2. DNA fragments are separated according to their size.
3. Under the influence of electric field, positively charged molecules move towards the anode and negatively charged molecules move towards the cathode.
4. None of these.

5. The factor that will not affect the rate of DNA migration in gel electrophoresis is:

1. Size of DNA molecule.
2. Concentration of DNA.
3. Voltage supplied.
4. Concentration of the gel.

Read the following and answer any four questions from (i) to (v) given below:

Tools used in the formation of recombinant DNA are of three types. These are enzymes, cloning vectors and competent host. lysing enzymes are used to extract DNA for experimental purpose from the cells. Cleaving enzymes break the DNA molecules. TI1ey are of three types : exonucleases, endonucleases and restriction endonucleases. A competent host is required for transformation with recombinant DNA and cloning vectors help to propagate DNA.

1. Which of the following is an example of natural Iysing activity in a human body?

1. Lysozyme present in tears dissolve the bacterial cell wall.
2. Conversion of starch to maltose in the buccal cavity
3. Absorption of digested food into the intestinal cells.
4. Conversion of protein molecules into amino acids in the stomach.

2. Which of the following depicts exonuclease activity?

1.  

2.  

3.  

 

4. All of these

3. Cloning vectors are the DNA molecules that.

1. Carry foreign DNA segment but do not replicate inside the host cell.
2. Carry foreign DNA segment and replicate inside the host cell.
3. Transfer nuclear DNA form nucleus to the cytoplasm of the same cells.
4. Help in sealing gaps in DNA segments.

4. Transfer of DNA into a eucaryotic cell is called:

1. Transformation.
2. Transduction.
3. Transfection.
4. Electroporation.

5. Assertion: Type I restriction enzymes are not used in rDNA technology.

Reason: Biotechnology mostly involves cutting and pasting of desired DNA fragments.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Read the following and answer any four questions from (i) to (v) given below:
Villagers in a place near Chambur started planning to make power supply for agricultural purposes from cow dung. 'Tiley have started a biogas plant for the purpose. Study the flow chart for biogas production given below and answer the following questions.

1. Biagas is composed of majorly:

1. Methane, CO₂ and O₂
2. CO₂, H₂S and H
3. Methane, CO₂
4.  H₂S, H and O₂

2. In the given flow chart, 'A' denotes:

1. Aerobic bacteria.
2. Methanogenic bacteria.
3. Cellulose degrading bacteria.
4. Yeast and protozoa.

3. What is represented by 'B' in the flow chart?

1. Carbohydrates.
2. Protein polymers.
3. Organic acids.
4. Fat globules.

4. 'C' in the given flow chart causes:

1. Aerobic breakdown of complex organic compounds.
2. Anaerobic digestion of complex organic compounds.
3. Fermentation of organic compounds.
4. Fermentation of monomers.

5.  If 'A' is not added in the procedure.

1. Methane will not be formed.
2. CO₂ will not be formed.
3. Organic compounds will not be converted to H₂S
4. O₂ will not be formed.

Explain the methods for making host cell competent to insert the r DNA.

Read the following and answer any four questions from (i) to (v) given below:

The mature ovum or a female gamete is spherical in shape. The human ovum is almost free of yolk and is said to be alecithal. Human ovum loses its ability to be fertilised about 24 hours after ovulation. Refer to the given structure of ovum and answer the following questions.

1. Thick cellular layer formed of radially elongated follicular cells is:

1. Zona pellucida.
2. Plasma membrane.
3. Perivitelline membrane.
4. Corona radiata.

2. In humans, at which stage does ovum get released from ovary?

1. Secondary oocyte.
2. Oogonium.
3. Primary oocyte.
4. First polar body.

3. Cytoplasm of an ovum is enveloped by _____.

1. Zona pellucida.
2. Corona radiata.
3. Cell membrane.
4. Perivitelline space.

4. Select the correct option:

S. No	V	W	X
(a)	Cytoplasm	Zona pellucida	Plasma membrane
(b)	Cortical granules	Corona radiata	Zona pellucida
(c)	Cortical granules	Plasma membrane	Corona radiata
(d)	Cytoplasm	Corona radiata	Zona pellucida

5. Which of the following is not a characteristic of an ovum?

1. Nucleus of an ovum has prominent nucleolus.
2. Only one ovum formed from one oogonium.
3. It lacks centrioles.
4. It has very small amount of ooplasm.

Read the following and answer any four questions from (i) to (v) given below:

ln many species of fig trees, there is a tight one-to-one relationship with the pollinator species of wasp. It means that a given fig species can be pollinated only by its 'partner' wasp species and no other species. The wasp pollinates the fig inflorescence while looking for suitable egg-laying sites. ln return for the favour of pollination, the fig offers the wasp some of its developing seeds as food for the developing wasp larvae.

1. The interaction between fig trees and wasp is an example of:

1. Mutualism
2. Commensalism
3. Amensalism
4. Parasitism

2. AD the given interactions are similar to interaction between fig trees and wasp, except.

1. Plant and animal relation for pollination.
2. Association of algae and fungi in lichens.
3. Association of cattle egret and grazing cattle.
4. Association of fungi and roots of higher plants in mycorrhiza.

3. In which of the following interactions both partners are adversely affected?

1. Parasitism
2. Mutualism
3. Competition
4. Predation

4. ln relationship between fig and wasp:

1. One benefitted other harmed.
2. Both are benefitted.
3. One benefitted other unaffected.
4. One inhibited, other unaffected.

5. Assertion: Fig and wasp cannot complete their life cycle without each other.

Reason: They show mutualistic relationship.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Read the following and answer any four questions from (i) to (v) given below:

Each testicular globule of testis contains one to three highly coiled seminiferous tubules. Wall of each seminiferous tubule is formed of single layered germinal epithelium. Majority of cells in this epithelium are cuboidal, called male germ cells. Study the transverse section of part of seminiferous tubule and answer the following questions.

1. What is the characteristic of K?

1. K is spermatogonium which grows into primary spermatocyte.
2. K is Sertoli cell which provides nutrition to spermatids.
3. K is secondary spermatocyte which undergo meiosis II to form spermatid.
4. K is spermatid being converted into sperm.

2. Which of the following cell undergo reduction division to form secondary spermatocyte?

1. J
2. M
3. L
4. K

3. How many among the following have 46 chromosomes?

1. 2
2. 4
3. 5
4. 3

4. Select an option that correctly identifies different labels.

1. L- Primary spermatocyte, N - Spermatozoa, M - Secondary spermatocyte.
2. J - Spermatogonium, K - Sertoli cell, O - Spermatozoa.
3. L- Primary spermatocyte, M - Secondary spermatocyte, N - Spermatozoa.
4. J - Spermatogonium, K - Primary spermatocyte, N - Spermatid.

5. Which hormone initiates spermatogenesis at puberty?

1. FSH
2. ICSH
3. ABP
4. GnRH