Category: Class 12 Biology Objective Questions

250+ TOP MCQs on Food Production Strategies – Plant Breeding-1 and Answers

Biology Multiple Choice Questions on “Food Production Strategies – Plant Breeding-1”.

1. Who is the father of the Green revolution in India?
a) M.S. Swaminathan
b) Charles Darwin
c) Herbert Boyer
d) Stanley Cohen
Answer: a
Clarification: M.S. Swaminathan has been regarded as the father of green revolution in India. Green Revolution not only met the national requirements in food production of our country but also helped us to explore it.

2. Which phase is often referred to as the Green Revolution?
a) The Mid-1900s
b) The Mid-1980s
c) The early 2000s
d) The Mid-1960s
Answer: d
Clarification: The phase of the mid-1960s is often referred to as the green revolution in India. The development of several high yielding varieties of wheat and rice in the mid-1960s, as a result of various plant breeding techniques, led to a dramatic increase in food production in our country.

3. GDP stands for __________
a) General Disorder of Pancreas
b) Gross Domestic Product
c) Good Domestic Price
d) Goods Delay Price
Answer: b
Clarification: GDP stands for Gross Domestic Product. India is mainly an agricultural country. Agriculture accounts for approximately 33 per cent of India’s GDP and employs nearly 62 per cent of the population.

4. Which of the following is not related to plant breeding?
a) Helped to increase the yield of crops
b) Purposeful manipulation of plant species
c) Gives disease-resistant plants
d) Not suited for cultivation
Answer: d
Clarification: Plant breeding is the purposeful manipulation of the plant species in order to create desired plant types that are better suited for cultivation, give better yields and are disease resistant. Plant breeding as technology has helped increase yields to a very large extent.

5. Recorded evidence of plant breeding dates back to 20,000 years ago.
a) True
b) False
Answer: b
Clarification: Conventional plant breeding has been practised for thousands of years, since the beginning of human civilisation; recorded evidence of plant breeding dates back to 9,000-11,000 years ago. Many present-day crops are the result of domestication in ancient times.

6. Which of the following is not involved in classical plant breeding practices?
a) The hybridisation of pure lines
b) Artificial selection of plants
c) Desirable traits of higher yield
d) Molecular biology
Answer: d
Clarification: Classical plant breeding involves crossing or hybridisation of pure lines, followed by artificial selection to produce plants with desirable traits of higher yield, nutrition and resistance to diseases. With advancements in genetics, molecular biology and tissue culture are also being carried out.

7. Which of the following is not a trait that should be incorporated in a crop plant?
a) Decreased tolerance to environmental stresses
b) Increased yield
c) Resistance to pathogens
d) Increased tolerance to insect pests
Answer: a
Clarification: Traits or characters that the breeders have tried to incorporate into crop plants are increased crop yield, improved quality, increased tolerance to environmental stresses (salinity, extreme temperatures, drought), resistance to pathogens (viruses, fungi and bacteria) and increased tolerance to insect pests.

8. Where are Plant breeding experiments generally carried out?
a) Colleges
b) Schools
c) Government institutions
d) Botanical gardens
Answer: c
Clarification: Plant breeding programmes are carried out in a systematic way worldwide in government institutions and commercial companies. With advancements in genetics, molecular biology and tissue culture, plant breeding is now increasingly being carried out by using molecular genetic tools.

9. Which of the following is not the main step in carrying out plant breeding technique?
a) Collection of variability
b) Cross hybridisation among the diseased parents
c) Selection and testing of superior recombinants
d) Evaluation and selection of parents
Answer: b
Clarification: The main steps in breeding a new genetic variety of a crop are-Collection of variability, Evaluation and selection of parents, cross hybridisation among the selected parents, selection and testing of superior recombinants; testing, release and commercialisation of new cultivars.

10. Which of the following step is the main root of any plant breeding programme?
a) Genetic variability
b) Evaluation and selection of parents
c) Cross hybridisation among the selected parents
d) Selection and testing of superior recombinants
Answer: a
Clarification: Genetic variability is the root of any breeding programme. In many crops, pre-existing genetic variability is available from wild relatives of the crop. Collection and preservation of all the different wild varieties, species and relatives of the cultivated species is a pre-requisite for effective exploitation of natural genes available in the population.

11. The selected plant while breeding is multiplied and used in the process of hybridisation.
a) False
b) True
Answer: b
Clarification: The germplasm is evaluated so as to identify plants with a desirable combination of characters. The selected plants are multiplied and used in the process of hybridisation. Pure lines are created wherever desirable and possible.

12. Which of the following is not included in germplasm collection?
a) Wild relatives
b) Old improved varieties
c) Diseased varieties
d) Pure lines
Answer: c
Clarification: The entire collection of plants or seeds having all the diverse alleles for all genes in a given crop is called as germplasm collection. It consists of all present-day improved varieties, old improved varieties no longer in cultivation, local varieties of all areas, pure lines maintained by plant breeders, wild relatives and related species.

250+ TOP MCQs on Microbes in Industrial Products-4 and Answers

Biology Assessment Questions for Schools on “Microbes in Industrial Products-4”.

1. Which of the following is not an industrial product of microbe?
a) Antibiotics
b) Bioactive molecules
c) Toddy
d) Beverages
Answer: c
Clarification: Toddy is not an industrial product of microbes. Microbes are used to synthesise several products valuable to human beings. Some of the industrial products of microbes include antibiotics, bioactive molecules, enzymes, beverages, etc.

2. What does the given figure represent?

a) Fermentor
b) Reactor
c) Activator
d) Eliminator
Answer: a
Clarification: This is a pictorial representation of fermentors.

Fermentors are very large vessels in which microbes are grown on an industrial scale and their products are used for various commercial purposes.

3. What does antibiotic mean?
a) Against life
b) Towards life
c) Without life
d) With biotics
Answer: a
Clarification: Anti is a Greek word that means ‘against’ and bio means ‘life’, together they mean ‘against life’ (in the context of disease-causing organisms). These antibiotics kill the bacteria or slows down their rate of their reproduction.

4. Who discovered the full potential of an antibiotic?
a) Alexander Fleming
b) Ernest Chain
c) Ernst Haeckel
d) Louis Pasteur
Answer: b
Clarification: The full potential of an antibiotic (Penicillin discovered at that time) was established by Ernest Chain and Howard Florey. This antibiotic was extensively used to treat American soldiers wounded in World War II.

5. After Penicillin, other antibiotics were also purified from other microbes.
a) True
b) False
Answer: a
Clarification: After Penicillin, other antibiotics were also purified from other microbes. For example, Erythromycin is obtained from Streptomyces erythreus, Bacitracin is obtained from Bacillus subtilis, Neomycin from Streptomyces fradiae, etc.

6. Which of the following organism is used to obtain Streptokinase?
a) Yeast
b) Bacteria
c) Protozoa
d) Algae
Answer: b
Clarification: Streptokinase is produced by the bacterium Streptococcus and is modified by genetic engineering to be used as a clot-buster from removing clots from the blood vessels of patients who have undergone myocardial infarction leading to a heart attack.

7. What is the full form of TPA?
a) Tissue plasminogen activator
b) Tissue plasma activator
c) Tract of Pancreas
d) Thymus-Pancreas Activator
Answer: a
Clarification: Streptokinase is also called as Tissue Plasminogen Activator or TPA which is obtained from haemolytic Streptococcus species and modified genetically to be useful in human beings.

8. Which of the following is used as an immunosuppressant?
a) Cyclosporin A
b) Statin
c) Streptokinase
d) Penicillin
Answer: a
Clarification: Cyclosporin A is used as an immunosuppressant agent in the organ transplant patients and is produced by the fungus Trichoderma polysporum.

9. Statins are produced by a fungus.
a) True
b) False
Answer: b
Clarification: Statins are produced by the yeast Monascus purpureus and it has been commercialized as blood-cholesterol-lowering agent. It acts by competitively inhibiting the enzyme responsible for the synthesis of cholesterol.

10. Which of the following is not a correct statement regarding steroids?
a) Used medicinally in correcting hormonal imbalance
b) Complex crystallisable lipids
c) Constituents of the cell membrane
d) Deficiency causes scurvy
Answer: d
Clarification: Steroids are complex crystallisable lipids. They are constituents of cell membranes, hormones and some important biochemical like cholesterol, progesterone, oestrogen, testosterone, etc. They are also used medicinally for correcting hormonal imbalance.’

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250+ TOP MCQs on Biotechnological Applications in Medicine: Genetically Engineered Insulin and Answers

Biology Multiple Choice Questions on “Biotechnological Applications in Medicine: Genetically Engineered Insulin”.

1. How many recombinant therapeutics have been approved for humans to date?
a) 30
b) 20
c) 13
d) 25
Answer: a
Clarification: Recombinant therapeutics is the type of medicines obtained from recombinant organisms. These are mostly protein in nature. Till date, 30 recombinant therapeutics have been approved for human use which includes insulin, human factor IX, etc.

2. Out of 30 how many recombinant therapeutics have been marketed in India?
a) 10
b) 12
c) 30
d) 14
Answer: b
Clarification: Out of 30 how many recombinant therapeutics 12 have been marketed in India. These products have been approved by the Genetic Engineering Appraisal Committee (GEAC). Few examples of approved products are Human growth hormone, Human insulin, Erythropoietin, etc.

3. From which animals were insulin obtained in the early days?
a) Insects
b) Lizard and snakes
c) Cats and dogs
d) Cattle and pigs
Answer: d
Clarification: In early days the insulin was obtained from the pancreas of cattle and pigs. Insulin obtained this way had many disadvantages. Nowadays insulin is obtained using recombinant DNA technology. For this microorganisms are used.

4. How many polypeptide chains does insulin consist of?
a) 4
b) 3
c) 2
d) 1
Answer: c
Clarification: Insulin consists of two polypeptide chains. These are known as A chain and B chain. A chain is made up of 21 amino acids while the B chain is made up of 30 amino acids. Thus, making insulin a polypeptide containing 51 amino acids.

5. The polypeptide chains present in insulin is connected by _______ bonds.
a) ionic
b) covalent
c) disulphide
d) hydrophobic interactions
Answer: c
Clarification: The polypeptide chains present in insulin is connected by disulphide bonds. These disulphide bonds are formed between two cysteine residues. In total insulin consists of 3 disulphide bonds.

6. Which organ secretes insulin?
a) Stomach
b) Pancreas
c) Thyroid
d) Intestine
Answer: b
Clarification: Insulin is secreted by the pancreas. The stomach secretes various digestive enzymes like pepsin and gastric juice. The thyroid secretes thyroid hormones while small intestine secretes trypsin.

7. In mammals insulin is secreted as __________
a) enzyme
b) lipid
c) RNA
d) pro-hormone
Answer: d
Clarification: Insulin is a pro-hormone secreted in mammals by the pancreas. This pro-hormone need to be processed to become a fully mature and functional hormone. Insulin allows the absorption of glucose I blood.

8. Insulin in pro-hormone form contains an extra stretch called _______
a) B-peptide
b) G-peptide
c) C-peptide
d) S-peptide
Answer: c
Clarification: The pro-hormone form of insulin consists of an extra stretch called C-peptide. The C peptide is a connecting peptide having approximately 31 amino acids. It connects A and B chain of pro-insulin.

9. _________ is absent in the mature insulin.
a) Lipid
b) A-peptide
c) C-peptide
d) Sequence
Answer: c
Clarification: C-peptide is absent in mature insulin. This connecting peptide connects A and B chain in pro-insulin. It is removed during the maturation of pro-insulin to insulin.

10. ______ in 1983 used recombinant DNA technology to produce insulin.
a) Eli Lilly
b) Emily Lilly
c) Lilly Rose
d) Amy Sanger
Answer: a
Clarification: In 1983 Lilly Company of America that was founded by Eli Lilly used recombinant DNA technology to produce insulin. This insulin was obtained from a microorganism.

11. ______ organism was used to produce recombinant insulin.
a) Cyanobacteria
b) E.coli
c) Saccharomyces cerevisiae
d) B. subtilis
Answer: b
Clarification: The first recombinant insulin was constructed by using E.coli. It was developed by Lilly Company. E.coli was used because it has a large circular plasmid that can act as a vector, requires less growth time and can be easily grown in a laboratory.

12. C-peptide is removed during ______ phase of insulin.
a) initiation
b) maturation
c) termination
d) elongation
Answer: b
Clarification: C-peptide is removed during the maturation phase of insulin production. C-peptide consists of 30 amino acids and it joins two insulin polypeptide chains in pro-insulin. It is released as a by-product of insulin formation.

250+ TOP MCQs on Organisms and Populations – Adaptations – 2 and Answers

Biology Question Papers for Class 12 on “Organisms and Populations – Adaptations – 2”.

1. What is a population?
a) Species of a community
b) Individuals in the same species
c) Individuals in a family
d) Communities in an ecosystem
Answer: b
Clarification: Population is the level of the organization after an organism. Various organisms come together and start residing at the same place known as population. The population includes organisms of the same group or species.

2. What are the populations of the different species which live and interact together in the ecosystem called?
a) Community
b) Kingdom
c) Genera
d) Species
Answer: a
Clarification: A group of populations is known as a community. It is a group of people who share the same place or live within the same area. These people may share common characteristics. It is the organizational level between population and ecosystems.

3. What are the interactions between organisms in a community called?
a) Physical interaction
b) Biological interaction
c) Psychological interaction
d) Chemical interaction
Answer: b
Clarification: The interactions between organisms in a community are called biological interaction. They may include organisms of the same species or different species. The interactions between organisms are essential for survival and the proper functioning of the ecosystem.

4. What are the modifications of the organisms living on the land for their survival called?
a) Aquatic
b) Aerial
c) Arboreal
d) Terrestrial
Answer: d
Clarification: The modifications of the organisms living on the land for their survival called terrestrial adaptations. It is exhibited by all organisms, plants as well as animals. These adaptations are for various biological activities.

5. Which of the following is an adaptation for running?
a) Desert
b) Arboreal
c) Cursorial
d) Terrestrial
Answer: c
Clarification: The adaptation for running is known as cursorial adaptation. It is an adaptation for fast running to find hiding places for protection from various predators. Some examples of cursorial animals are deer, horse, cockroach, leopard, etc.

6. What is an adaptation for climbing and balancing called?
a) Fossorial
b) Arboreal
c) Cursorial
d) Terrestrial
Answer: b
Clarification: The adaptation for climbing and balancing is known as arboreal adaptation. It is also known as scansorial adaptation. It is used by animals for climbing on trees, rocks, walls, etc. This type of adaptation is shown by monkeys, sloths, chameleons, koalas, etc.

7. Which among the following is a characteristic of arboreal adaptation?
a) Longer loop of Henle
b) Long prehensile tail
c) Short limbs
d) Hind limbs provided with longer toes
Answer: d
Clarification: Hind limbs provided with longer toes are a characteristic of arboreal adaptation. Along with this arboreal animals have a long prehensile tail (monkeys) with strong and stout limbs. They also have opposable digits (marsupials) and elongated claws (squirrels).

8. Which among the following has adapted for arboreal adaptation?
a) Pigeon
b) Rat
c) Monkey
d) Camel
Answer: c
Clarification: Monkey is an example of arboreal adaptation. It has strong and stout limbs, long prehensile tail along with opposable digits. Because of these adaptations they can easily climb on trees, walls.

9. What is an adaptation for survival in the desert called?
a) Terrestrial adaptation
b) Fossorial adaptation
c) Arboreal adaptation
d) Desert adaptation
Answer: d
Clarification: The adaptation for survival in the desert is called desert adaptation. It is a mode of life in extreme terrestrial habitats. These animals have thick and hard skin and are nocturnal. They have a longer loop of Henle for more water reabsorption.

10. Which of the following has adapted for desert adaptation?
a) Monkey
b) Peacock
c) Camel
d) Pigeon
Answer: c
Clarification: Camel is an animal adapted for desert adaptation. It stores water in all body tissues. They also have a hump made up of fatty tissue. They have longer Henle’s loop in kidneys.

11. What is an adaptation for an aquatic mode of life called?
a) Fossorial
b) Aquatic
c) Volant
d) Arboreal
Answer: b
Clarification: The adaptation for aquatic life is called aquatic adaptation. They have large spindle-shaped streamlined bodies. Their skin is rich in mucous glands and has gills for the absorption of dissolved oxygen.

12. Which adaptation is a feature of fishes?
a) Hollow bones
b) Presence of longer loop of Henle
c) Streamlined bodies and scales
d) Presence of beak
Answer: c
Clarification: Streamlined bodies with scales are a characteristic feature of fishes. They have gills for the absorption of dissolved oxygen and also have an air bladder that helps in floating in the water.

13. What is an adaptation for flying called?
a) Arboreal
b) Volant
c) Desert
d) Aquatic
Answer: b
Clarification: The adaptation for flying or gliding is called volant adaptation. These animals have lighter bodies as compared to other species. These organisms have wings with feathers, hollow spongy bones along with larger hearts.

14. Among the following whose feature is a hollow body with pneumatic or spongy bones?
a) Fishes
b) Tigers
c) Cockroach
d) Birds
Answer: d
Clarification: Hollow body with pneumatic or spongy bones is a feature of birds. They have boat-shaped sternum, thin cranial bones, and beaks that help in the reduction of body weight by providing lightness to ease flight.

15. In which organisms left ovary and oviduct are present?
a) Birds
b) Mammals
c) Plants
d) Reptiles
Answer: a
Clarification: Only left ovary and oviduct are present in birds. Many organs such as right ovary and oviduct, gall bladder, urinary bladder are either absent or vestigial to reduce body weight, provide lightness and ease in flying.

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250+ TOP MCQs on Ecosystem – Decomposition and Answers

Biology Multiple Choice Questions on “Ecosystem – Decomposition – 1”.

1. Which organism is said to be a farmer’s friend?
a) Rat
b) Earthworm
c) Bat
d) Leopard
Answer: b
Clarification: The earthworm is said to be a farmer’s friend. The earthworm is a tubular, segmented invertebrate organism commonly found in soil that survives on eating live and dead organic matter. They improve the health of the soil by break down soil substances and loosening it.

2. Which are the organisms called those who are responsible for the break down complex organic matter into inorganic substances?
a) Decomposers
b) Producers
c) Consumers
d) Herbivores
Answer: a
Clarification: The organisms that are responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances are called decomposers (detritivores). The decomposers or detritivores may include invertebrates, fungus or bacteria.

3. What is the process of break down complex organic matter into inorganic substances called?
a) Organization
b) Decomposition
c) Production
d) Consumption
Answer: b
Clarification: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. It is carried out by the organisms called decomposers (invertebrates, fungus or bacteria).

4. What are the complex organic remains such as dead animal remains, dead plant remains, and fecal matter called?
a) Humus
b) Mucus
c) Excreta
d) Detritus
Answer: d
Clarification: The organic remains such as dead plants remain, dead animal remains and fecal matter is called detritus. It acts as the raw material for various organisms such as decomposers. In terrestrial ecosystems, it is called “soil organic matter” while in the aquatic system it is known as “marine snow”.

5. Which organisms carry out the fragmentation of detritus?
a) Sponges
b) Vertebrates
c) Detritivores
d) Zooplankton
Answer: c
Clarification: The process of fragmentation of detritus is done by detritivores. These are also known as decomposers and are the organisms responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances.

6. Which of the following is an example of detritivore?
a) Monkey
b) Termites
c) Elephant
d) Flat-worm
Answer: b
Clarification: Among the above-given options, a termite is one of the best examples of detritivores. They are essential as they keep the forests healthy. They feed on dead decaying plants and aerate the soil as they move through it.

7. What is the process of secretion of digestive enzymes by decomposers to convert insoluble complex organic molecules into simple soluble organic and inorganic molecules called?
a) Fragmentation
b) Decomposition
c) Humification
d) Catabolism
Answer: d
Clarification: The process of secretion of digestive enzymes by decomposers to convert insoluble complex organic molecules into simple soluble organic and inorganic molecules is called catabolism. It is the catabolic metabolism in which degradation occurs.

8. What is the process called when detritivores feed on larger pieces and leave smaller fragments behind?
a) Leaching
b) Catabolism
c) Fragmentation
d) Mineralization
Answer: c
Clarification: The process called when detritivores feed on larger pieces and leave smaller fragments behind is called fragmentation. It is carried out by many detritivores such as carrion beetles, earthworms, termites, etc.

9. What is the process of the formation of a dark-colored amorphous substance called?
a) Leaching
b) Catabolism
c) Fragmentation
d) Humification
Answer: d
Clarification: The process of formation of dark-colored amorphous substance is called humification. This substance is called humus that is highly resistant to any microbial action and decomposes at a slower rate.

10. What is the dark amorphous organic matter rich in cellulose and lignin that is highly resistant to any microbial action and decomposes at a slower rate called?
a) Fragments
b) Enzymes
c) Humus
d) Minerals
Answer: c
Clarification: The dark amorphous organic matter rich in cellulose and lignin that is highly resistant to any microbial action and decomposes at a slower rate is called humus. It is formed due to the decomposition of the organic remains such as dead plants remains dead animal remains and fecal matter.

11. What is the percolation of the soluble substances formed due to decomposition called?
a) Humification
b) Leaching
c) Mineralization
d) Catabolism
Answer: b
Clarification: The percolation of the soluble substances formed due to decomposition into deeper layers of soil is called leaching. In this process, the water-soluble inorganic nutrients get precipitated as unavailable salts by going down into the soil horizon.

12. Which substances are formed along with humus due to the decomposition process?
a) Organic substances
b) Minerals
c) Inorganic substance
d) Fragments
Answer: c
Clarification: The substances are formed along with humus due to the decomposition process are inorganic nutrients. This gives rise to many metal ions such as iron, cobalt, potassium, selenium, zinc, etc.

13. What is the process of release of inorganic substances both minerals and non-minerals from organic matter called?
a) Fragmentation
b) Mineralization
c) Humification
d) Leaching
Answer: b
Clarification: The process of release of inorganic substances both minerals (H2O, CO2, etc.) and non-minerals from organic matter (e.g. Ca2+, NH4, Mg2+, K+, etc.) is called mineralization. It is the last step in the process of decomposition. These minerals are again used by plants for food production.

14. How many steps are involved in the process of decomposition?
a) 10
b) 2
c) 8
d) 5
Answer: d
Clarification: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. The decomposition is a 5 step process. The steps are fragmentation, leaching, catabolism, humification, and mineralization respectively.

15. What does decomposition depend on?
a) Oxygen
b) Nitrogen
c) Ammonia
d) Carbon monoxide
Answer: a
Clarification: The process of break down complex organic matter (dead or decaying organisms) into inorganic substances is called decomposition. It is an aerobic process and is largely dependent on the availability of oxygen.

250+ TOP MCQs on Ecosystem – Phosphorus Cycle and Answers

Biology Multiple Choice Questions on “Ecosystem – Phosphorus Cycle”.

1. Which one of the following is a major constituent of biological membranes, nucleic acids, and cellular energy transfer systems?
a) Potassium
b) Phosphorous
c) Selenium
d) Cobalt
Answer: b
Clarification: The phosphorous is the second most abundant mineral of the human body and constitutes 1 % of the total body weight. It is one of the following is a major constituent of nucleic acids, biological membranes, and cellular energy transfer systems.

2. Which of the following component is used to make shells, bones, and teeth by animals?
a) Phosphorous
b) Sodium
c) Gallium
d) Argon
Answer: a
Clarification: The phosphorous is one of the following is a major constituent of nucleic acids, biological membranes, and cellular energy transfer systems. It is also used to make shells, bones, and teeth by animals.

3. Who is the natural reservoir of phosphorous?
a) Atmospheric gases
b) Rocks
c) Water
d) Dead organisms
Answer: b
Clarification: The sedimentary rocks are known as the natural reservoir of phosphorous. They contain phosphorous in the form of phosphates known as phosphorite. It contains almost 4% to 20% of phosphate.

4. Which element is not released during respiration in the atmosphere?
a) Nitrogen
b) Cobalt
c) Carbon
d) Phosphorous
Answer: d
Clarification: The respiration is the process in which the organisms exchange gases with the environment. In this, the organisms take in the atmospheric oxygen for various cellular activities and release carbon dioxide. Phosphorous is not released during respiration in the atmosphere.

5. How is the gaseous exchange of phosphorus between organisms and the environment?
a) Maximum
b) Moderate
c) Negligible
d) No exchange
Answer: c
Clarification: The phosphorous is one of the following is a major constituent of nucleic acids, biological membranes, and cellular energy transfer systems. Unlike carbon, there is a negligible exchange of gaseous phosphorus between organisms and the environment.

6. Which one of the following is the simplified sequence of phosphorus cycling in a terrestrial ecosystem?
a) Soil → Producers → Rock minerals → Consumers → Decomposers
b) Rock minerals → Soil → Producers → Consumers → Decomposers
c) Rock minerals → Decomposers → Producers → Consumers
d) Decomposers → Rock minerals → Consumers → Producers
Answer: b
Clarification: The phosphorous cycle starts with rock materials and ends with the decomposers. The phosphorous enters the ecosystem through rock minerals and, there is a negligible exchange of gaseous phosphorus between organism and environment.

7. How do herbivores and other animals obtain phosphorous?
a) Soil
b) Rocks
c) Water
d) Plants
Answer: d
Clarification: The phosphorous is one of the following is a major constituent of nucleic acids, biological membranes, and cellular energy transfer systems. The plants are the source of phosphorous for herbivores and other animals.

8. Which of the biochemical cycle is without an atmospheric component?
a) Nitrogen cycle
b) Oxygen cycle
c) Phosphorous cycle
d) Carbon cycle
Answer: c
Clarification: The sedimentary rocks are known as the natural reservoir of phosphorous. It enters in the ecosystem through rock minerals. The biochemical cycle is without an atmospheric component is the phosphorous cycle.

9. Which of the following is a major constituent of DNA and RNA?
a) Calcium
b) Cobalt
c) Selenium
d) Phosphorous
Answer: d
Clarification: The phosphorous is one of the following is a major constituent of nucleic acids, biological membranes, and cellular energy transfer systems. It is the second most abundant mineral of the human body and constitutes 1 % of the total body weight.

10. Which biogenetic element is obtained from crystalline rocks?
a) Argon
b) Helium
c) Phosphorous
d) Magnesium
Answer: c
Clarification: The crystalline, sedimentary rocks are known as the natural reservoir of phosphorous. They contain phosphorous in the form of phosphates known as phosphorite. It contains almost 4% to 20% of phosphate.

11. Which of the following is known as the natural reservoir of phosphorous?
a) Fossils
b) Rocks
c) Animals
d) Water
Answer: b
Clarification: The crystalline, sedimentary rocks are known as the natural reservoir of phosphorous. They contain phosphorous in the form of phosphates known as phosphorite. It contains almost 4% to 20% of phosphate.

12. The phosphate by weathering of rocks firstly becomes available to which organisms?
a) Decomposers
b) Consumers
c) Producers
d) Detritivores
Answer: c
Clarification: The phosphorous enters in the ecosystem through the weathering of rock minerals. This phosphorous then enters soil that is taken up by the producers. Then it is passed on to consumers and then to decomposers.

13. In which form do the producers directly provide phosphorous to detritus?
a) Weathering
b) Litterfall
c) Fecal matter
d) Salts
Answer: b
Clarification: The dead plant materials that falls on the ground in the form of litter are known as litterfall. This litter includes leaves, bark, needles, twigs, cladodes, etc. It also consists of some amount of soil.

14. What is the killing of aquatic life due to the depletion of oxygen because of the excessive growth of algae due to the over-abundance of phosphorous in the coastal areas called?
a) Leaching
b) Respiration
c) Photosynthesis
d) Eutrophication
Answer: d
Clarification: Eutrophication is the process that leads to the killing of aquatic life due to the depletion of oxygen because of the excessive growth of algae due to the over-abundance of phosphorous in the coastal areas. Eutrophication is also known as hypertrophication and is the result of an increase in minerals in a water body.