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The correct answer is (B) Sucker

a. Students must have observed leaf tip tendril. 

b. In some weak stems, leaf apex modifies into thin, green, wiry, coiled structure called as leaf tendril. 

c. Such leaf tendrils, help in climbing by curling around a support.

a. Student must have observed an epiphytic plants like Dendrobium, Vanda growing on other plant. 

b. The two types of roots exhibited by this plant must be clinging roots and epiphytic roots. 

c. Clinging roots: 

1. Clinging roots are tiny roots develop along intemodes, show disc at tips. 

2. It exudes sticky substance which enables plant to get attached to the substratum without damaging it. 

d. Epiphytic roots: 

1. Epiphytic plants like Vanda, Dendrobium grow on branches of trees in dense rain forests and are unable to obtain moisture from soil.

2. Such plants produce epiphytic roots which hang in the air. 

3. The roots are provided with a spongy membranous absorbent covering of the velamen tissue. 

4. The cells of velamen tissue are hygroscopic and have porous walls, thus they can absorb moisture from air. 

5. Epiphytic roots can be silvery white or green and are without root cap.

The correct answer is (A) Gloriosa

Epiphytic roots: 

1. Epiphytic plants like Vanda, Dendrobium grow on branches of trees in dense rain forests and are unable to obtain moisture from soil. 

2. Such plants produce epiphytic roots which hang in the air. 

3. The roots are provided with a spongy membranous absorbent covering of the velamen tissue. 

4. The cells of velamen tissue are hygroscopic and have porous walls, thus they can absorb moisture from air. 

5. Epiphytic roots can be silvery white or green and are without root cap.

The frost can seriously damage the leaves and fruit of plants. When a farmer waters his fields, during, night, this water gives large amount of heat energy, because 1g of water will liberate 4.2J of energy for every 1°C fall in temperature. Thus, the air around the field is saturated with heat energy and its temperature does not fall below 0°C. Thus, no frost is formed.

Nodulated roots are found in leguminous plants.

a. Plants growing in marshy region (halophytes) produce upwardly growing roots called as pneumatophores or respiratory roots. 

b. The main root system of these plants does not get sufficient air for respiration as soil is water logged. 

c. Due to this, mineral absorption of plant also gets affected.

d. To overcome this problem underground roots, develop special roots which are negatively geotropic; growing vertically upward.

e. These roots are conical projections present around main trunk of plant.

f. Respiratory roots show presence of lenticels which helps in gaseous exchange.

(i) Tap root : The roots which develops from radicle along with its branches is termed as tap root. Secondary root develops from tap root. 

(ii) Fibrous Root : In monocot plants, the primary root is short lived and is replaced by roots that arise from the stem. These roots constitute the fibrous roots. 

(iii) Adventitious root: Roots which arise from other part of the plant except radical, are termed as adventitious roots.

Plank roots/Buttress: 

a. These roots often develop at the base of large trees and form plank like extensions around stem. 

b. These roots provide additional support, e.g. Silk cotton, Peepal, etc.

(i) Clinging root : These are non-absorptive adventitious roots which are found in climbers The clinging roots penetrate the cracks or fissures of the support. They hold the support firmly by forming claws. E.g., Pothos (Money plant) Betel, Black pepper etc. 

(ii) Stilt root: They are short, thick supporting roots which develop from the lower nodes of the stem. Examples : Sugarcane, Maize,

Process of Microsporogenesis in Angiosperms: 

(i) When the anther develops, each cell of sporogenous tissue functions as microspore another cell (MMC) or pollen mother cell (PMC) and undergoes is meiotic divisions to form microspore tetrads.

(ii) The process of formation of microspores from a pollen mother cell (PMC) through meiosis is called microsporogenesis. 

(iii) The microspores get arranged in a cluster of four cells and hence are microspore tetrad. 

(iv) As the anthers mature and dehydrate, the microspores dissociate from each other and develop into pollen grains. 

(v) In each microsporangium, thousands of pollen grains are formed and released with the dehiscence of anther.

Climbing roots: 

Different climbers with weak stem produce roots at their nodes by means of which they attach themselves to support and thereby raise themselves above the ground. e.g. Betel leaf or Pan, black pepper or Piper nigrum (Kali Mirch), Pothos or money plant.

1. Stilt roots: 

a. These roots normally arise from a few lower nodes of a weak stem in some monocots, shrubs and small trees.

b. They show obliquely downward growth penetrating soil and provide mechanical support to the plant. 

c. In the members of family Poaceae, the plants like Maize, Jowar, Sugarcane etc. produce stilt root in whorl around the node. 

d. These roots provide additional support to the plant body.

e. In Screw pine or Pandanus (Kewada), stilt roots arise only from the lower surface of obliquely growing stem for additional support. These roots show multiple root caps.

2. Climbing roots: 

Different climbers with weak stem produce roots at their nodes by means of which they attach themselves to support and thereby raise themselves above the ground. e.g. Betel leaf or Pan, black pepper or Piper nigrum (Kali Mirch), Pothos or money plant.

Somatic Hybridisation

• The process of fusion of protoplast of somatic cells obtained from different varieties or species of plant on a suitable nutrient medium in vitro to develop a somatic hybrid is called somatic hybridisation.

• It is carried out by the following steps:

i. Single cells from selected plants are isolated.

ii. The cell walls of cells are digested by enzymes like pectinase and cellulase, to expose the naked protoplasts.

iii. Naked protoplasts surrounded only by plasma membranes are isolated.

iv. The isolated protoplasts are fused to obtain hybrid protoplasts under sterile conditions in special nutrient media.

v. The hybrid protoplasts are cultured in a suitable media to form new plant.

• Pomato is an example of a somatic hybrid produced by fusion of tomato and potato protoplasts.

Uses:

i. Somaclonal variations can be created by this method.

ii. The plant which failed to produce sexual hybrid may produce somatic hybrids.

iii. Healthy plants can be recovered from diseased plants.

(a) Diploid : Meiocyte :: Haploid : Camete.

(b) Male flower : Stamens :: Female flower : Pistils.

(c) Unisexual : Cross-prollination :: Bisexual : Self - poiiinatio.

These prop roots show secondary growth, become thick, act like pillars to provide mechanical support to the heavy branches.

It is carried out by the following steps:

i. Single cells from selected plants are isolated.

ii. The cell walls of cells are digested by enzymes like pectinase and cellulase, to expose the naked protoplasts.

iii. Naked protoplasts surrounded only by plasma membranes are isolated.

iv. The isolated protoplasts are fused to obtain hybrid protoplasts under sterile conditions in special nutrient media.

v. The hybrid protoplasts are cultured in a suitable media to form new plant.

Algae and Bryophytes.

The name given is hermaphrodite. Other examples include earthworm and leech.

The technology that has helped the scientists to propagate on large scale the desired crops is tissue culture or micropropagation.

The steps to propagate crops are:

i. Obtaining an explant from a plant.

ii. Growing the explant in a test tube under sterile conditions.

iii. A special nutrient or culture medium is provided for growth.

Antherozoids have to travel through water to reach upto archegonia. Large number of antherozoids get wasted before reaching upto the archegonia. Hence Iarge number of antherozoids are produced and only a few egg cells.

Male gametes need a medium to move towards female gametes for fertilisation. In simple plants such as bryophytes and pteridophytes, the transfer of gamete takes place through water medium. To compensate the loss of male gametes during transport, a large number of male gametes are produced.

The capacity of a cell/explant to grow into a whole plant is called totipotency.

Requirements:

i. Explant: Any part of a plant taken out and grown in a test tube.

ii. Nutrient medium: It must have carbon source (sucrose), inorganic salts, growth regulators (auxins, cytokinins, etc.), vitamins and amino acids.

iii. Suitable light and temperature conditions.

Totipotency is defined as the capacity of any plant cell to generate a whole plant. 

Requirements are

• An explant, i.e. any part/tissues of a tomato plant
• Nutrient medium containg a carbon source like sucrose, inorganic salts, aminoacids, vitamins and growth regulators like auxins and cytokinins.
• Sterile conditions.

Medium should provide carbon source such as sucrose, inorganic salts, vitamins and growth regulators like auxins, cytokinins etc. It evens give required moisture.

(a) A large-scale propagation of desired crop in a short duration can be carried out with the help of micropropagation or tissue culture technique. The main steps of tissue culture technique are as follows: 

(i) Preparation of nutrient medium : A suitable nutrient medium is prepared and transferred into containers under aseptic conditions. 

(ii) Selection of explants : Explants are taken preferably from the meristematic regions (apical or axillary buds or the modal sections) of the desired crop plants. 

(iii) Sterilization of explants : The explants are surface sterilized by disinfectant like sodium hypochlorite and then washed by sterile distilled water. 

(iv) Inoculation : Inoculation (transfer) of explants into previously sterilized nutrient medium under aseptic conditions. 

(v) Incubation : The cultures are kept for incubation in the growth chamber under suitable cultural conditions. 

(vi) Regeneration : After incubation for a few days the explants give rise to an undifferentiated mass of cells called callus from which in due course of time a number of plantlets come out. 

(vii) Hardening : The regenerated plantlets are acclimatized gradual exposure to the environmental conditions 

(viii) Plantlets Transfer : The plantlets are transferred to green House or field after their acclimatization (Hardening). 

(b) Somatic hybrids are obtained by somatic hybridization a process of fusing the protoplast of two different somatic cells obtained from different varieties or species of plants under optimal cultural conditions. The main steps of somatic hybridization are 

(i) Isolation of single cells from two different plants having desired characteristics or traits. 

(ii) Digestion of their cell wall with the help of enzymes like cellulase and pectinases.

(iii) Isolation of naked protoplast. 

(iv) Fusion of two protoplasts by spontaneous fusion or by induced fusion. 

(v) Growth of hybrid protoplast : The hybrid protoplast is further grown to form somatic hybrid. A new hybrid plant named as pomato has been developed by this technique. This has the characteristics both tomato and potato.

The healthy, virus-free potato plants can be obtained from virus infected desired potato variety by meristem culture (Tissue culture technique) because meristems are not affected by viruses, they remain virus free even in the plants affected by virus. Explants from the meristematic regions like apical or axillary buds or from the nodal segments are taken and cultured on the solid medium enriched by cytokinin and auxin in suitable ratio under aseptic condition. Adventitious roots and shoots develop from the explant resulting in the formation of new plantlets which are finally transferred to the field.

Even though a plant is infected by a virus, the area meristem (apical or axillary) is free of virus. So the meristem can be removed and grown in vitro in sterile condition and special nutrient/ culture medium.

Based on the explanin some other plant tissue culture

types are: 

1. Organ culture 

2. Meristem culture 

3. Protoplast culture 

4. Cell culture

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We have provided Biotechnology and its Applications Class 12 MCQ Questions with Answers to help students understand the concept very well. MCQ Questions for Class 12 Biology with Answers were prepared based on the latest exam pattern. 

Solving the MCQ Questions of Class 12 Biology can be of extreme help as you will be aware of all the concepts thereby helping you to enhance subject knowledge. Practice the given MCQ Questions for your better preparation. Many questions have been asked from this topic in past board and medical exams, and therefore, It is imperative that students study this chapter thoroughly. To aid you in your preparation, we have handpicked a few MCQ Questions which we deem important from a learning perspective.

Practice MCQ Question for Class 12 Biology chapter-wise

1. Restriction Endonuclease used in RDT obtained from:

(a) Plasmid
(b) Bacterial cells
(c) Bacterophages
(d) All Prokaryotic cells

2. Some bacterial occured B-7 Toxin’s crystal not kill the Bacteria because of:

(a) Bacteria is Antoxin
(b) Toxin is unripened
(c) Toxin is inactive
(d) Bacteria enclosed toxin a special sell

3. First Transjenic crop was :

(a) Cotton
(b) Alsi
(c) Pea
(d) Tobacco

4. Adjoining of exotic gene is crop is called :

(a) Genetic Engineering
(b) Bio architecture
(c) Tissue culture
(d) Immunisation

5. Cry protein is obtained from

(a) Bacillus thuringiensis
(b) Bacillus subtilis
(c) Clostridium welchi
(d) E. coli

6. B7 Toxin is :

(a) Intracellular lipid
(b) Intracellular crystal protein
(c) Extracellular Crystal protein
(d) Lipid

7. Somatic hybridization can be done by:

(a) By Protoplast fusion
(b) By Haploid anther
(c) By cell culture
(d) ByPollen culture

8. The Ti plasmid used in genetic engineering is obtained from:

(a) Bacillus thruingiensis
(b) E. Coli
(c) Agrobacterium hizogenes
(d) Agrobacterium tumefaciens

9. From which one of the following plants, the insecticide pyrethrum is prepared.

(a) Cymohopogen
(b) Tephrosia
(c) Crysanthemum
(d) Vitivera

10. First biochemical to be produced commercially by microbial cloning and genetic engineering:

(a) Human insulin
(b) Penicillin
(c) Interferons
(d) Fertility factor

11. Anticoagulant hirudin is found in:

(a) In Snake
(b) In Lizard
(c) In Leech
(d) In Scorpion

12. ..... .is used as a vector for cloning into higher organisms

(a) Retrovirus
(b) Baculovirus
(c) Salmonella typhimurium
(d) All of these

13. Production of human protein in bacteria by genetic engineering is possible because

(a) Genetic code is universal
(b) Bacterial cell can undertake RNA splicing
(c) Mechanism of gene regulation is identical in human and bacteria
(d) None of these

14. The site of production of ADA in the body is

(a) Lymphocytes
(b) Bone marrow
(c) Blood plasma
(d) Monocytes

15. The trigger for activation of toxin of Bacillus thuringiensis is

(a) Alkaline pH of gut
(b) Mechanical action in the insect gut
(c) High temperature
(d) Acidic pH of stomach

16. Clot buster obtained from Streptococcus and modified by genetic engineering is

(a) Streptokinase
(b) Penicillin
(c) Cyclosporin A
(d) Statins

17. Domestic cooking gas cylinder is filled with

(a) Alcohol
(b) Diesel oil
(c) Liquid petroleum gas
(d) Coal gas

18. Which group is not related with petroplantation

(a) Euphorbiaceae
(b) Asclepiadiaceae
(c) Apocyanaceae
(d) Leguminaceae

19. The pioneer country in the production of 'Fuel alcohol' is

(a) Japan
(b) Brazil
(c) Saudi Arabia
(d) India

20. Conversion of sugar into alcohol during fermentation is due to the direct action of

(a) Temperature
(b) Microorganisms
(c) Zymase
(d) Concentration of sugar solution

21. Bacillus thuringiensis (Bt) strains have been used for designing novel             

(a) Bio-metallorgical techniques
(b) Bio-insecticidal plants
(c) Bio-mineralization processes
(d) Bio-fertilizers

22. Cry genes introduced in a plant will not be affective against

(a) lepidoptera
(b) hymenoptera
(c) coleoptera
(d) rodents

23. Which of the following is used to manufacture ethanol from starch

(a) Penicilline
(b) Lactobacillus
(c) Azotobactor 
(d) Saccharomyces

24. A genetically engineered micro-organism used successfully in bioremediation of oil spills is a species of:

(a) Pseudomonas
(b) Trichoderma
(c) Xanthomonas
(d) Bacillus

25. Maximum number of existing transgenic animals is of

(a)  mice
(b)  cow
(c)  pig
(d)  fish

Answer :

1. Answer : (b) Bacterial cells

Explanation: Restriction endonucleases used widely in RDT are obtained from bacterial cells.

2. Answer : (c) Toxin is inactive

Explanation: Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because toxin is inactive . In bacteria, the toxin is present in an inactive form, called prototoxin, which gets converted into active form when it enters the body of an insect.

3. Answer : (d) Tobacco

Explanation: Transgenic crops are disease resistant, pest resistant, environmental change-resistant and etc. Complete answer: The world's first genetically modified crop is the tobacco plant, which produced in 1982; this plant was antibiotic-resistant.

4. Answer : (a) Genetic Engineering

Explanation: Genetic engineering is the process of using recombinant DNA (rDNA) technology to alter the genetic makeup of an organism. Genetic engineering involves the direct manipulation of one or more genes. Most often, a gene from another species is added to an organism's genome to give it desired phenotype.

5. Answer : (a) Bacillus thuringiensis

Explanation: Cry proteins are a large family of crystalline toxins produced by Bacillus thuringiensis. Individually, the family members are highly specific, but collectively, they target a diverse range of insects and nematodes.

6. Answer : (b) Intracellular crystal protein

Explanation: A gene from Bt toxin has been cloned from the bacteria and is expressed into plants to provide resistance to pests without the need for insecticides. It secretes toxin extracellularly, which is a crystalline protein that blocks insect gut proteins upon ingestion.

7. Answer : (a) By Protoplast fusion

Explanation: Somatic hybridization is the technique that allows manipulation of the cellular genome by a process called protoplast fusion. It is a type of genetic modification in plants by which two distinct species of plants are fused together to form a new hybrid plant with the characteristics of both.

8. Answer : (d) Agrobacterium tumefaciens

Explanation: One of these is the Ti plasmid from the soil-borne bacterium Agrobacterium tumefaciens. It is the most promising vector to date for plant genetic engineering.

9. Answer : (c) Crysanthemum

Explanation: Pyrethrum is also the name of a natural insecticide made from the dried flower heads of Chrysanthemum cinerariifolium and Chrysanthemum coccineum. Its active ingredient are pyrethrins.

10. Answer : (a) Human insulin

Explanation: Recombinant DNA technology was first used commercially to produce human insulin from bacteria. In 1982, genetically engineered insulin was approved for use by diabetics. People with certain types of diabetes inject themselves daily with insulin, a protein hormone that regulated blood sugar.

11. Answer : (c) In Leech

Explanation: The anticoagulant hirudin, which is extracted from the body tissues of the European medicinal leech (Hirudo medicinalis), is used to prevent blood clots following surgery; another chemical isolated from Amazonian leeches is used to dissolve existing blood clots.

12. Answer : (a) Retrovirus

Explanation: Vectors used for cloning genes into higher organisms are retroviruses.

13. Answer : (a) Genetic code is universal

Explanation: We all know that genetic codes are universal. The order of nucleotides is the same that will result in incorporation of the same amino acid during the process of translation. That is why the production of human protein is possible through genetic engineering.

14. Answer : (a) Lymphocytes

Explanation: The main site of production of ADA in the body is lymphocytes [a form of small leucocyte (white blood cell) with a single round nucleus, occurring especially in the lymphatic system and which plays a large role in defending the body against disease.

15. Answer : (a) Alkaline pH of gut

Explanation: Bt toxins are initially inactive protoxins but after ingestion by the insect these inactive toxin becomes active due to the alkaline pH of the gut which solublise the crystals. Hence, high pH value is required to make Bt toxins active.

16. Answer : (a) Streptokinase

Explanation: Streptokinase (Tissue Plasminogen Activator or TPA) is an enzyme obtained from the cultures of some haemolytic bacterium Streptococcus and modified genetically to function as clot buster.

17. Answer : (c) Liquid petroleum gas

Explanation: LPG, which is heavier than air due to its high density, is a hydrocarbon-based combustible gas. LPG is the generic name of the butane and propane gases and their mixtures in different proportions. In Turkey, LPG used in household gas cylinders consists of 70% butane and 30% propane.

18. Answer : (d) Leguminaceae

Explanation: The important petrol plants belong to Euphorbiaceae, Apocynaceae, Asclepiadaceae, and Urticaceae. The family which does not have petro plants is Leguminosae.

19. Answer : (b) Brazil

Explanation: Brazil is the world's largest sugarcane ethanol producer and a pioneer in using ethanol as a motor fuel.

20. Answer : (c) Zymase

Explanation: Conversion of sugar into alcohol during fermentation is due to the direct action of zymase. Zymase is the protein that changes the basic sugars, dextrose, and fructose into carbon dioxide gas and liquor at 37 C, and a few esters bring about creating the interesting fragrance, flavor, and taste of bread.

21. Answer : (b) Bio-insecticidal plants

Explanation: Bacillus thuringiensis strains have been used for designing bio insecticidal plants. A gene from this bacteria have insecticidal property which is transferred to cotton plants to produce Bt cotton which is resistant I to bollworm insect which is a major pest of cotton.

22. Answer : (d) rodents

Explanation: Cry gene produce toxin protein that chocks the gut of insects in presence of alkaline pH to cause death of insects. It is not effective against rodents.

23. Answer : (d) Saccharomyces

Explanation: The first step is saccharification, where starch is converted into sugar using an amylolytic microorganism or enzymes such as glucoamylase and α-amylase. The second step is fermentation, where sugar is converted into ethanol using Saccharomyces cerevisiae.

24. Answer : (a) Pseudomonas

Explanation: Bioremediation is the process of using living micro-organisms to clean up a contaminated site. Organisms that produce enzymes capable of degrading petroleum are useful in cleaning up oil spills. Some common ones that break down oil are genetically engineered species of Pseudomonas and Azotobactera.

25. Answer : (a)  mice

Explanation: Mice are the most commonly used species for these purposes, but transgenic animals have been produced in a variety of livestock.

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(Germs pores) to allow pollen tube to emerge out/ pollen germination.

Detailed Answer

Exine does not form a continuous layer around the pollen grain. Exine and hence sporopollenin is absent over certain specific regions which are called germ pores. Germ pores serve as outlet for the growth and emergence of pollen tube.

(a) Microspore mother cell   →16, which is a diploid (2n) number.

(b) Endosperm  → 24 -- Because it is a triploid (3n) structure, formed as a result of triple fusion i.e, the fusion of one male gamete with two haploids (n) polar nuclei or with a diploid secondary nucleus. 

Vaccine is an antigen protein of pathogens or inactivated or weakened pathogens or their toxin. When it is introduced into the body of a person who is required to be made immune it stimulates the production of antibody and memory cell which is called primary response. It does not cause harm when this pathogen enters second time. These memory cells show rapid and massive responses so body become immune to this pathogen.

In apomixis or agamospermy, seeds are formed without the fusion of gametes. Diploid cells of the nucellus or integuments develop into an embryo, giving diploid seeds with a genetic constitution identical to the parent. Apomixis takes place in orange and onion.

Production of CO₂ gas during yeast fermentation of bacteria.

Single parent ,two parents with or without gamete formation , fusion of gametes.

Fertilization of haploid egg cell by one haploid male gamete, to form diploid zygote, is called syngamy. Fertilization of two polar nuclei by the other haploid male gamete, to from triploid primary endosperm nucleus, is called triple fusion. The fertilization thus occurs twice in the embryo sac. Therefore it is called as double fertilization.

Zygote is formed by fusion of male gamete (n) and egg cell (n), hence diploid (2n). 

Primary endosperm nucleus is formed by the fusion of two polar nuclei or secondary nucleus (n + n) and male gamete (n), hence triploid (3n).

Production of CO₂ during fermentative activity of yeast mixed with flour.

i. Selection among somaclonal variants

ii. Genetic engineering.

Pollen grains.

Steps for producing disease resistant plants are:

i. Screening of germplasm (for resistance sources)

ii. Hybridisation of selected parents

iii. Selection and evaluation of hybrids

iv. Testing and release of new varieties.

Algae and fungi.

Morphologically and genetically similar off springs are produced through tissue culture called somaclones. Isolation of somatic cells from two different varieties Digestion of cell wall using enzymes.

Fusion of protoplast of two different varieties forming somatic hybrid protoplast. Culture of protoplast hybrid to produce somatic hybrid.