Students must start practicing the questions from CBSE Sample Papers for Class 12 Biology with Solutions Set 8 are designed as per the revised syllabus.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Time Allowed: 3 Hours
Maximum Marks: 70

General Instructions:

  1. ALt questions are compulsory.
  2. The question paper has five sections and 33 questions. ALL questions are compulsory.
  3. Section-A has 16 questions of 1 mark each: Section-B has S questions of 2 marks each; Section-C has 7 questions of 3 marks each: Section-D has 2 case-based questions of 4 marks each, and Section-E has 3 questions of 5 marks each.
  4. There is no overall choice. However, internat choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
  5. Wherever necessary, neat and properly Labeled diagrams should be drawn.

Section – A (16 Marks)

Question 1.
Match the following and choose the correct option.

Column I Column II
(A) Mammary Lobes (i) Its ceLls secrete milk which is stored in its cavities.
(B) Alveoli (ii) Stores milk during lactation.
(C) Lactiferous sinuses (iii) In each breast, it is 15-20 in numbers.
(D) Mammary ampulla (iv) it is formed by joining of several mammary ducts.

Options:
(a) (A)-(ii), (B)-(i), (C)-(iii), (D)-(iv)
(b) (A)-(iii), (B)-(iv), (C)-(ii), (D)-(i)
(c) (A)-(iii), (B)-(i), (C)-(ii), (D)-(iv)
(d) (A)-(ii), (B)-(iv), (C)-(iii), (D)-(i)
Answer:
1. (c) (A)-(iii), (B)-(i), (C)-(ii), (D)-(iv)

Explanation:
The chest region contains a pair of mammary glands that contain glandular tissue and fat. Each breast’s glandular tissue contains 15-20 mammary lobes that contain clusters of cells known as alveoli. Alveolar cells secrete milk, which is stored in the alveolar cavities or Lumen. The alveoli connect to the mammary tubules. Each lobe’s tubules connect to form a mammary duct. Just under the nipples of mammary glands, lactiferous ducts widen to form the Lactiferous sinuses to store milk during lactation. The mammary ampulla is formed by the union of several mammary ducts, and the ampulla is Linked to the lactiferous duct, through which milk is sucked out.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 2.
The given figure represents ……………. structures and these are said to be the result of …………… evolution.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 1

(a) Analogous: convergent
(b) Analogous: divergent
(c) Homologous: convergent
(d) Homologous: divergent
Answer:
(a) Analogous: convergent
Explanation:
The given figure represents the analogous structures and these are said to be the result of convergent evolution because they are not anatomically similar structures though they perform similar functions.

Question 3.
Study the following figure.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 2

identify (I) and (II)

(I) (II)
(a) Homozygous recessive (a) Homozygous dominant
(b) Homozygous dominant (b) Homozygous recessive
(c) Heterozygous dominant (c) Heterozygous recessive
(d) Heterozygous recessive (d) Heterozygous dominant

Answer:

(b) Homozygous dominant (b) Homozygous recessive

Explanation:
Homozygous means that the organism has two copies of the same allele for a gene. An organism can be homozygous dominant, if it carries two copies of the same dominant allele, or homozygous recessive, if it carries two copies of the same recessive allele.

Question 4.
Rahul recorded the productivity of some plants during a survey. Look at the graph given below:

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 3

Which of the given category represents the primary productivity of coral reefs and estuaries?
(a) Category 1
(b) Category 2
(c) Category 3
(d) Category 4
Answer:
(d) Category 4
Explanation: In an aquatic ecosystem, highest rate of primary productivity is represented by the coral reefs and estuaries.

Related Theory
Primary productivity is defined as the amount of biomass Or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight (gm-2) or energy (kcal m-2).

Question 5.
Name the phenomena which relates the picture shown here.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 4
(a) Lamarckism
(b) Adaptations
(c) Connecting links
(d) Adaptive radiation
Answer:
(d) Adaptive radiation
Explanation: Darwin’s finches represent one of the best examples of adaptive radiation. The process of evolution of different species in a given geographical area starting from a point and radiating to other areas is called adaptive radiation.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 6.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 5

Avenn diagram is shown, identify ‘X’ and ‘Y

X Y
(a) NationaL parks Biosphere reserves
(b) Biosphere reserves Sanctuaries
(c) National parks Botanical gardens
(d) Botanical gardens National parks

Answer:

(a) NationaL parks Biosphere reserves

Explanation: National parks are meant for protection of entire ecosystem (both flora and fauna). Biosphere reserves are Teaming places for sustainable development’. They are sites for testing interdisciplinary approaches to understanding and managing changes and interactions between social and ecological systems, including conflict prevention and management of biodiversity.

Question 7.
Biologists of India developed genetically modified brinjaL What is the main reason behind this development?
(a) Insect resistance
(b) insect growth
(c) Bacterial resistance
(d) All of these
Answer:
(a) Insect resistance
Explanation: Biologists of India developed genetically modified brinjal for insect or pest resistance. In genetically modified crops, Bt- genes are present which are responsible for the production of toxin that kills insects.

Question 8.
Observe the given diagram carefully and identify A:
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 6

(a) H1
(c) H3
(b) H2
(d) H4
Answer:
(a) H1
Explanation: H1 histone, also known as Tinker histone,’ is important in determining the compaction state of an array of nucleosomes and influencing their conformation.

Question 9.
……………. and ……………. both comes under Mendel’s monahybrid crass.
(a) Law of independent assortment, law of segregation.
(b) Law of dominance, law of segregation
(c) Law of dominance, law of independent assortment
(d) Law of inheritance, law of dominance 1
Answer:
(b) Law of dominance, law of segregation
Explanation: Law of dominance, law of segregation both comes under Mendel’s monohybrid cross. This is considered as inheritance of one gene. On the other hand, law of independent assortment comes under Mendel’s dihybrid cross.

Question 10.
includes not only the physical space occupied by an organism but also its functional roles in the community.
(a) Niche
(b) Habitat
(c) Migration
(d) Gene flow
Answer:
(a) Niche
Explanation: Niche describes the role that organisms play in a community. The physical and environmental requirements (such as temperature or topography) and interactions with other species that a species must tolerate make up its niche (like predation or competition).

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 11.
Which of the following pair is correctly matched?
(a) Parthenium hysterophorus – Threat to biodiversity
(b) Stratification – Population
(c) Aerenchyma – Opuntia
(d) Age pyramid – Biome
Answer:
(a) Parthenium hysterophorus – Threat to biodiversity
Explanation:
Parthenium hysterophorus a weed that harms wheat plants, poses a threat to biodiversity. It causes dermatitis and respiratory issues in people.

Related Theory:
→Vertical layering of flora and fauna is known as stratification.
→Aerenchyma cells are parenchyma cells with extensive intercellular gaps filled with air. They keep the aquatic plants buoyant and aid in their flotation. The xerophytic plant opuntia can endure extremely dry circumstances.
→Age pyramid: This diagram shows how the population is distributed by age group. The biodiversity and environment collectively make up the biome

Question 12.
An example of an organism that enters ‘diapause’:
(a) Phytoplankton
(b) Zooplankton
(c) Fish
(d) Bird
Answer:
(b) Zooplankton
Explanation: Under unfavourable conditions, many zooplankton species in takes and ponds enter a stage of suspended development catted diapcuse.

Question 13.
Dr. Kalkuli Vittal Hegde is well known for his love of and concern for the Western Ghats rainforest. His passion for the area has inspired many environmental battles, the most significant of which was the fight to protect tribal villages and habitats inside the Kudremukh National Park and staunch opposition to the eviction of about 15,000 forest residents who lived in 36 commercial villages inside the national park.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 7

Assertion (A): Biodiversity hotspots are the regions with high species richness and endemism.
Reason (R): There are major four biodiversity hotspots in India, the Himalayas, Indo-Burma Region, the Western Ghats and Aravalli Hills.
Question No. 13 to 16 consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer:
(c) A is true but R is false.

Explanation: The term ‘Biodiversity hotspots’ is coined by Norman Myers. These are the regions with high species richness and S endemism. There are major four biodiversity hotspots in India, the Himalayas, Indo-Burma Region, the Western Ghats and Sundaland.

Question 14.
Assertion (A): Genital herpes is a common sexually transmitted infection. caused by an untreatable virus.
Reason (R): The herpes simplex virus (HSV) is the infectious agent of Genital herpes. 1
Answer:
(a) Both A and R are true and R is the correct explanation of A.
Explanation: Genital herpes is a common sexually transmitted infection caused by the herpes simplex virus (HSV). This virus is challenging to cure because of its nature. The HSV virus can hide away in a person’s nerve cells for months or years before reappearing and reactivating the infection.

Question 15.
Assertion (A): Charles Darwin is known as the father of evolution.
Reason (R): The process of evolution is continuously occurring in all organisms. 1
Answer:
(c) A is true but R is false.
Explanation: The process of evolution is stochastic, relying on random occurrences in nature and alter mutations in organisms.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 16.
Assertion (A): The first, restriction enzyme was Hind III.
Reason (R): The recognition sequence of the first isolated restriction enzyme was six base pair long. 1
Answer:
(d)Ais False but is true.
Explanation:
The first restriction enzyme was an endonuclease Hind IL It was isolated and characterized by Smith Wilcox and Kettey in 1968 from Haemophilus ¡nfluenzae. The enzyme Hind II was found to always cut DNA moLecules at a particular point by recognizing a specific sequence of six base pairs. This specific base sequence is termed as the recognition sequence for Hind Il.

Section – B (10 Marks)

Question 17.
Refer to the diagram given below and answer the questions that follow
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 8

(A) Cite the name of the tank marked ‘A
(B) During the process of biological sewage treatment, primary effluents are passed through Large ‘A’ tanks, why?
Answer:
(A) The tank marked ‘A’ is aeration tank.
(B) During the process of biological sewage treatment, primary effluents are passed through large aeration (A) tanks. It is done to allow the vigorous growth of useful aerobic microbes into floes, so that the amount of BOD is reduced.

Related Theory:
Floes are the masses of bacteria held together by slime and fungal filaments to form mesh like structures.

Question 18.
Khan and his friends visited to Leh and Lodakh. Most of the places here are 10,000 ft. or above and attitude or mountain sickness is a reality here.
(A) Mention two symptoms to diagnose attitude or mountain sickness.
(B) How could people recover from the [ow oxygen stress happened due to this at high altitudes?
Answer:
(A) The common symptoms to diagnose the attitude or mountain sickness are headache, nausea, heart palpitations and fatigue.
(B) Low oxygen stress happened due to this high altitude and the body recover from this by increasing the blood cell production, increasing the breathing rate and decreasing the binding affinity of haemoglobin.

Question 19.
Identify A, B, C and D in the following table with reference to birth control

Method Example
A Lippes Loop
B Tubectomy
Barrier C
D Saheli

Answer:
A- Non-medicated IUD, B-Female sterilisation, C- Cervical caps, D- Oral pill

Question 20.
The graph given shows on illustration of various types of human protein enriched milk. Out of aLl the categories, A, B, C and D, which category of milk is secreted by transgenic cow Rosie?

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 9

OR
In a pathological lab, a series of steps were undertaken for making a Genetically Modified Organism (GMO). Describe the steps, or make a flow chart showing the process of genetic engineering.
Answer:
Category B, /.e„ the milk with human a-lactalbumin is secreted by first transgenic cow Rosie. This milk was nutritionally a more balanced product for human babies than natural cow’s milk.
OR
The three basic steps of genetic engineering or making a Genetically Modified Organism (GMO) are:

  • Identification of DNA with desirable genes.
  • Introduction of the identified DNA into the suitable host to form recombinant DNA (rDNA).
  • Maintenance of introduced DNA in the host and transfer of the DNA to its progeny

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 21.
(A) Name the most common and widely used bioreactor in biotechnology labs. of large volume of desired product.
Answer:

  1. Stirring-type bioreactors are the most common and widely used bioreactor in biotechnology labs.
  2. Two components of bioreactor that is essential for the production of large volume of desired product are:
    • Agitator system
    • Oxygen delivery system
    • Foam control system
    • Temperature
    • pH control system
    • Sampling ports.

Question 22.
Given below is the dinucleotide structure:
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 10

  • Guanine base is attached to which sugar- ribose or deoxyribose. Also provide a reason for your answer.
  • Give the name of the linkage that tye the two nucleotides together.
  • Recognize the dinucleotide’s 3′ end. Give an explanation for your answer. 3

Answer:

  • Guanine base is attached to deoxyribose sugar as this sugar does not contain an additional -OH group at 2’ position.
  • The linkage that typing the two nucleotides together is 3’ – 5’ phosphodiester linkage
    B is the dinucleotide’s 3′ end because this polymer has a free 3’ -OH group.

Question 23.

  1. Define evolution.
  2. In the past, life was thought to have developed from the inorganic atmosphere of the earth, but this is no longer the case. Write two causes. 3

Answer:

  1. Evolution is the gradual change in the inherited traits of biological populations over many generations.
  2. The following factors make it impossible to create life in the environment of today:
    • The temperature of the atmosphere today is significantly lower than that of the atmosphere in prehistory.
    • Because oxygen is present in the atmosphere today, it is oxidising rather than reducing in nature.

Question 24.
Substantiate by giving three reasons as to why a human genome project was called a mega project?
Answer:
The reasons behind the Human genome project considered as a mega project are:
(1) Human genome has approximately 3 x 109 and if the cost of sequencing required

Question 25.
identify the wall layer ‘X’ of the structure of microsporangium shown below. State any four of its functions.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 11

OR
Describe about the hormonal control of menstrual cycle.
Answer:
X is the tapetum (innermost layer) of the microsporangium. The functions performed by this layer are:

  1. It transports supplements to the anthers.
  2. It expels ubisch bodies, which helps thicken the pollen grain membrane
  3. It also acts as a precursor source for the pollen wall or pollen coat
  4. It secretes the callase enzyme that breaks the callose compounds used to unite four pollens (pollen tetrad). Thus, they allow pollens from a tetrad to get separated.

OR
The beginning half of the menstrual cycle has the largest production of FSH, whereas the middle of the cycle sees the greatest secretion of LH. It is thought that the follicle ripens and ovulation occurs as a result of the sequential activity of FSH and LH. Although FSH and LH alone have been effectively used to stimulate ovulation in people receiving therapy for infertility.

Following the administration of high amounts of FSH, numerous births have taken place as a result of multiple ovulation. The pituitary gland stimulates the ovary to produce estrogens and progesterone, but there is a “negative feedback” by which the estrogens inhibit the output of FSH from the pituitary gland (and probably stimulate the output of LH). In addition, progesterone is believed to inhibit the further output of LH.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 26.
(A) Self-pollination is continuously performed in superior recombinants. State the reason why is it done?
(B) A flow chart of the steps which ensure that the seeds are formed only from the desired sets of pollen grains are given below. Fill the two blanks
(i) and
(ii) provided in between the steps.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 12

(C) Name the type of experiment that is shown in the above given flow chart. 3
Answer:
(A) Superior recombinants undergo multiple generations of self-pollination in order to achieve homozygosity or homogeneity. Thus, in the offspring, the characters won’t segregate.
(B) (I) represents emasculation and (II) represents pollination.
(C) The experiment or technique that is carried out to obtain seeds from a desired set of pollen grains is referred to as artificial hybridization.

Question 27.
(A) Why are bio-wastes in the tank of a gobar gas plant added with a slurry of cattle dung (gobar) to produce biogas?
(B) Why is “starter” used to get milk to curdle? Explain.
(Q Expand the term MALT. 3
Answer:
(A) The slurry known as gobar, which contains cow dung excrement, is a rich source of methanogen bacteria. It is utilised to produce biogas. These anaerobic bacteria, known as methane bacteria, break down the cellulose in dung to release gases like methane, C02, and H2.

(B) Millions of Lactic Acid Bacteria (LAB) present in the starter grow in milk and turn it into curd when a small bit of curd is given to new milk as a starter or inoculum. Acids released by the LAB during this process coagulate and partially breakdown the milk proteins (casein). The curd’s vitamin B12 content is increased by LAB, along with other vitamins.

(C) MALT stands for Mucosal Associated Lymphoid Tissue.

Related Theory:
MALT constitutes about 50 per cent of the lymphoid tissue in human body. It is present within the lining of the major tracts (respiratory, digestive and urogenital).

Question 28.
(A) Draw a diagram of a typical anatropous ovule and label.
(B) In females, which birth control method has 99% success rate? 3
Answer:
(A) The diagrammatic representation of a typical anatropous ovule is as follows:
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 19
(B) In females, tubectomy (sterilisation method) has 99% success rate.

Section – D (8 Marks)

(Q. No. 29 and 30 are case based questions. Each question has subparts with internal choice in one subpart.)

Question 29.
A seventeen-year-old white male comes into the family practice office you are staffing for a physical exam so he can serve as a counselor at scout summer camp. He is has been health and well since his last examination in fifth grade. He is presently 5 foot 7 inches and weighs 160 lbs. He is mildly pudgy and mild gynecomastia. His penis is 5.5 cm and testicles less than 2 cm. You are concerned about gonadal function.

Testes of a normal male looks like the following figure:
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 13

(A) Name the primary sex organs in males.
(B) Observe the given diagram.
In the figure, marked portion ‘X’ is the outermost covering of testis. Identify ‘X’.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 14

(i) Label (P) and (Q).
(ii) What is the function of (Q)?

OR
(C) (i) Testis, shown in the diagram are placed in a sac like structure which helps in keeping the temperature at a lower level (For optimal hormone production). Name the sac like structure.
(ii) Name the male sex accessory ducts.
Answer:
(A) Testes are the primary sex organs in males. These are also known as male gonads. Testes are the sites where male gametes, i.e. sperms are produced.
(B) ‘X’ is the tunica albuginea which is a dense fibrous membrane forms the outermost povering of testis.
(C) (i) P-Vas deferens Q-Bulbourethral gland.

(ii) Secretion of a penis lubricant. Explanation: Bulbourethral glands produce a mucus secretion which-provides a lubrication media to the urethra and penis, helps in taking out any residue of urine, dead cells through urethral meatus aiding ejaculation, removes acidity in the urethra as its secretions are alkaline.
OR
(i) Scrotum is a sac like structure which contains the testis. It maintains a lower temperature (2-2.5 degree Celsius lower than the body temperature) for spermatogenesis.
(ii) Rete testis, epididymis, Vasa efferentia and Vas deferens.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

Question 30.
Pradeep, a prominent businessman in Delhi, was born in a small village. During the festival of Diwali, he visited his village. The fact that ladies were still using cow dung cakes to prepare food there greatly distressed him. He made the decision to build the plant that is depicted in the image below so that people might utilize the gas that it produces for cooking. Pradeep received much gratitude from the villagers for his valuable support:

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 15

(A) Name the plant which is shown in the given image. 1
(B) Biogas production is done with the help of which bacterium. 1
(C) (i) The composition of biogas with blanks ‘A’, ‘B’ and ‘C’ is given in the pie chart below. Identify the % of ‘A’, ‘B’ and ‘C.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 16

(ii) What is required as a substrate for the production of biogas?
OR
(C) What is gobar gas? Name the bacteria responsible for its production. 2
Answer:
(A) Biogas plant
(B) Biogas production is done with the help of bacteria which are collectively known as methanogens, e.g., Methanobacterium.
(C) (1) A- 40-70%, 8- 25-55%. C- O-1%
(ii) Municipal. and household garbage
OR
(C) The bacteria responsibLe is Methanobacterium. This bacteria is also

Section – E (15 Marks)

Question 31.
When Akshay had an accident: local residents hurriedly took him to the hospital. The doctor noticed that excessive blood loss results from significant bleeding. Therefore, a blood transfusion is needed right away. For an urgent need of the rarest blood group, the hospital’s nurse phones a blood bank.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 17

(A) Name the rarest blood group.
(B) Which blood group is known as universal recipient and universal donor?
(C) Why can’t O-positive blood be transfused into Akshay’s body?
(D) What is the genetic basis of blood group inheritance?
OR
Draw a well-labelled diagram of a lac operon. Also explain about the switching on and switching off of the operon. 5
Answer:
(A) The rarest blood group is O negative.
(B) Blood group AB is known as universal recipient and O is known as universal donor.
(C) O positive blood group contains antigen for Rh factor. Rh- blood lacks the antigen, so if the two blood mix, it will cause clotting which results in the death of the patient.

(D) There are three genes that determine a man’s blood type. These three genes, or alleles, are all found in the same chromosomal location. Only two of these three genes, which can be identical or different in nature, can exist in a person at any given moment. These genes regulate how blood group antigen is produced in the progeny. There are three alleles- A, B, and O. Because both of the three human blood group alleles are expressed in the phenotypes A and B, the three alleles are referred to as codominant.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

OR
Switching ‘on’ of the operon: If lactose is added to the bacteria’s growth medium in the absence of a preferred carbon source such as glucose, the lactose is transported into the cells by the enzyme permease. This activates the operon, causing the following events to occur:

(1) The presence of an inducer, such as lactose or allolactose, inactivates the repressor due to inducer-repressor interaction (i.e binding of inducer to repressor). As a result, the inactive repressor is prevented from binding to the operator region.

(2) This allows RNA polymerase to access the promoter, after which transcription proceeds and lac mRNA, which is polycistronic and produces all three enzymes – p -galactosidase, permease, and transacetylase, is formed. As a result, the operon is activated.

Switching ‘off’ of the operon:
(1) In the absence of lactose, I gene regulates and produces the operon’s repressor.

(2) The repressor protein binds to the operon’s operator region, preventing RNA polymerase from transcribing the operon.

(3) In this case, the operon will be turned off. present in the rumen of cattle. The excreta of cattle is rich commonly called gobar is rich in these bacteria. Thus, dung can also be used for the generation of biogas commonly called gobar gas.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 20

Question 32.
In the field of medicine, recombinant DNA technology is crucial. Explain how this method was employed to create genetically modified human insulin using a flowchart. Also, draw a flow chart of maturation of pro-insulin into insulin.
OR
Write two advantages and three disadvantages of genetically modified crops. 5
Answer:
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 21

OR
Advantages of GeneticaLLy modified crops

  • Prevents early exhaustion of fertility of soil
  • More tolerant to abiotic stresses.

Disadvantages of Genetically modified crops

  • Con cause human health problems by altering the genes and transferring the antibiotic resistance.
  • Transgenic genes in GM crops may pose threat to native species.
  • Couse damage to environment by reducing biodiversity.

Question 33.
(A) The image shown below is of zonation in terrestrial biosphere. Explain about these three zones present in a biosphere reserve.
CBSE Sample Papers for Class 12 Biology Set 8 with Solutions 18
Answer:
(A) A biosphere reserve is divided into three zones:

  1. Core zone: It consists of an undisturbed and legally protected ecosystem where no human activity is permitted/no human interference is permitted.
  2. Buffer zone: A zone with little human activity that surrounds the core area.
  3. Transition zone: In this area, active .cooperation between reserve management and local people occurs, and thus human settlement, grazing cultivation, and other activities are permitted.

(B) Biosphere reserves set up under the MAB (Man and Biosphere) programme of UNESCO. It is an international biological programme. It started in 1971 and was introduced in India in 1986. It aims to establish a scientific basis for the improvement of relationships between people and their environments. MAB has studied human environment, impact of human interference and pollution on biotic and abiotic environments and conservation strategies for the present as well as for the future generations.

CBSE Sample Papers for Class 12 Biology Set 8 with Solutions

OR
Alpha Diversity:

  1. It is determined by counting the taxa-typically species-that are present in a certain area, community, or ecosystem.
  2. Take a mountain slope as an example. This hillside will include a range of forest and grassland sections.
  3. The number of different species present in each patch of forest or grassland on the slope is referred to as alpha diversity.

Beta Diversity:

  1. Calculating the species diversity between two neighboring ecosystems is based on the number of species that are specific to each area.
  2. Using the aforementioned slope as an example, beta diversity is the species diversity between any two patches and their communities on that specific slope.

Gamma diversity:
It refers to the habitat variety over the whole landscape or geographical area. In the example of the slope, the species variety along the full range of the mountain slope is referred to as the gamma diversity of the