Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “Population Interactions-1”.

1. What is the interaction between species in which the fitness of one overpowers the presence and fitness of another called?
a) Competition
b) Mutualism
c) Parasitism
d) Commensalism
Answer: a
Clarification: In competition interaction, the fitness of one organism overpowers the presence and fitness of another. In these organisms of same or different species, living in the same or different community fights for the same resources.

2. Who gave the following sentence “Two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior will be eliminated eventually”?
a) Gause’s competitive exclusion principle
b) Mutation Theory
c) Theory of Special Creation
d) Theory of Organic Evolution
Answer: a
Clarification: The above sentence is given by Gause’s competitive exclusion principle. It states that two species having the same resources cannot live together at constant population values. The inferior species will be eliminated with time due to natural selection.

3. Where the interference competition does occur directly between individuals?
a) Two species have a common prey
b) One individual prevents the reproduction of others
c) Organism compete for space
d) Two separate species compete for the same resources and space
Answer: b
Clarification: The interference competition is where one individual prevents the reproduction of others. Along with this, the survival of other species is also prevented. It can occur via aggression and is thought to stabilize consumer-resource systems.

4. Where exploitation competition does occur indirectly?
a) One individual prevents the survival and reproduction of others
b) Two species have common prey
c) Two separate species compete for different resources and space
d) Organisms compete for common space
Answer: d
Clarification: The exploitation competition occurs indirectly when organisms compete for common resources like space or territory, food or prey. It results in depletion in the availability and amount of resources.

5. In which two species apparent competition occurs indirectly?
a) Compete for space
b) Fight for the same resources and mate
c) Have a common prey
d) Share the same resources in a territory
Answer: c
Clarification: The apparent competition occurs indirectly between two species that fight for the same prey. In this, both the species may serve as prey for a common predator. It is an indirect negative interaction.

6. What is a competition between the individuals of two separate species for sharing the same resources in the same area known?
a) Apparent competition
b) Interspecific competition
c) Interference competition
d) Intraspecific competition
Answer: b
Clarification: Interspecific competition is the competition between the individuals of two separate species for sharing the same resources in the same area. An example is tigers and lions living in the same area competing for the same prey.

7. What is a biological interaction between organisms of different species in which each individual receives benefit known?
a) Parasitism
b) Competition
c) Commensalism
d) Mutualism
Answer: d
Clarification: Mutualism is a biological interaction between organisms of different species in which each individual receives a benefit. It is a positively directed relationship since both organisms are benefited.

8. What happens to two species in mutualism?
a) Only one is benefited
b) Both live differently
c) Both are benefited
d) Only one is harmed
Answer: c
Clarification: Mutualism is a biological interaction between organisms of different species in which each individual receives a benefit. It is a positively directed relationship since both organisms are benefited.

9. What kind of interaction is mutualism?
a) Negative Interspecific
b) Positive Intraspecific
c) Negative Intraspecific
d) Positive Interspecific
Answer: d
Clarification: Mutualism is a positively directed interspecific relationship. It is a biological interaction between organisms of different species in which each individual receives the benefit.

10. Who benefits the ungulates?
a) Sponges
b) Virus
c) Bacteria
d) Grass
Answer: c
Clarification: Bacteria living in the intestine of ungulates benefit them. Since many of them are herbivores the gut-bacteria help in the digestion of cellulose. Most of the gut-bacteria are anaerobic in nature.

11. Who produces the cellulase in the intestine of ungulates?
a) Bacteria
b) Mosses
c) Lichens
d) Protozoa
Answer: a
Clarification: Various bacterial species produce the cellulase in the intestine of ungulates. Since many of them are herbivores the gut-bacteria help in the digestion of cellulose. Most of the gut-bacteria are anaerobic in nature.

12. Which type of interaction does a mycorrhiza show?
a) Predation
b) Parasitism
c) Mutualism
d) Commensalism
Answer: c
Clarification: Mycorrhiza is a mutualistic interaction between fungi and plants. About 80-90 percent of plants rely on mycorrhiza for the uptake of minerals (nitrogen, phosphorous, etc.) from the soil. While plants supply essential nutrients such as sugars to fungi for their proper growth.

13. What percent of land plants rely on mycorrhizal relationships?
a) 82%
b) 52%
c) 29%
d) 10%
Answer: a
Clarification: Almost 80% of plants rely on the mycorrhizal relationship. Mycorrhiza is a mutualistic interaction between fungi and plants. Plants rely on mycorrhiza for the uptake of minerals (nitrogen, phosphorous, etc.) from the soil, while plants supply essential nutrients such as sugars to fungi for their proper growth.

14. Which relation does “sharing of food” describes?
a) Competition
b) Mutualism
c) Parasitism
d) Commensalism
Answer: d
Clarification: The phrase “sharing of food” or “sharing of the table” describes commensalism. It is a long-term relationship between two species in which one species derives the benefit while other is neither harmed nor benefited.

15. Which relationship does an orchid growing as an epiphyte on a tree describe?
a) Commensalism
b) Mutualism
c) Parasitism
d) Amensalism
Answer: a
Clarification: An orchid growing on epiphyte is an example of commensalism. Epiphytes grow on trees for air and sunlight while the tree is not harmed due to its presence. Another epiphyte growing on trees is a fern.

Biology Multiple Choice Questions on “Biodiversity Conservation”.

1. What is an important reason for the conservation of natural resources?
a) Disturb the ecological balance
b) Preserve the biological diversity
c) Disruption of quality of the environment
d) Hampering the biological species
Answer: b
Clarification: The materials or substances occurring in nature that exist without the actions of humankind are known as natural resources. The conservation of natural resources is important for the preservation of natural, biological diversity.

2. For what reason is the conservation of natural resources important?
a) Maintaining the ecological processes
b) Disturbing the ecological balance
c) Extinction of biological species
d) Disruption of quality of the environment
Answer: a
Clarification: The materials or substances (biotic and abiotic) occurring naturally and without the actions of humankind are known as natural resources. The conservation of natural resources is important for the preservation of biological diversity and maintaining ecological processes.

3. What is the correct full form of IUCN?
a) International Union for Conservation of Nuts
b) International Union for Conservation of Nature
c) International Union for Conservation of Natural habitat
d) International Union for Conservation of Numbers
Answer: b
Clarification: International Union for Conservation of Nature (IUCN) was founded on 5 October 1948 in France by Julian Huxley. It is working in the field of conservation of nature and sustainable use of natural resources.

4. What are the species called whose number of individuals is greatly reduced to a critical level?
a) Indeterminate
b) Rare
c) Vulnerable
d) Endangered
Answer: d
Clarification: Those species whose number of individuals is greatly reduced to a critical level and are at a high risk of extinction in the wild are known as endangered species. Some examples of endangered species are Brown spider monkey, Bengal tiger, Ganga river dolphin, Indian Rhino, Black buck, etc.

5. What are the species called whose number of individuals is greatly reduced recently and is decreasing continuously?
a) Endangered
b) Rare
c) Vulnerable
d) Indeterminate
Answer: c
Clarification: Those species whose number of individuals is greatly reduced recently and is decreasing continuously and are at a high risk of endangerment in the wild are known as vulnerable species. Some examples of vulnerable species are Barasingha, Nilgiri Langur, Yak, Olive Ridley Turtle, Sloth bear, etc.

6. What are the species called whose members are few and live in a small geographical area called?
a) Endangered
b) Rare
c) Indeterminate
d) Vulnerable
Answer: b
Clarification: Those species called whose members are few and live in a small geographical area and are very uncommon, scarce, or infrequently encountered are known as rare species. Some examples of rare species are Malabar Giant Squirrel, Gee’s Golden Langur, Dugong, Indian Giant Flying Squirrel, etc.

7. What are the species called whose members are in danger of extinction but the reason is unknown called?
a) Endangered
b) Vulnerable
c) Rare
d) Indeterminate
Answer: d
Clarification: The species called whose members are in danger of extinction but the reason is unknown, no enough information is available to decide their true nature are called indeterminate species. Some examples of intermediate species are Short-eared rabbit of Sumatra, Three-banded armadillo of Brazil, Rhinoceros, etc.

8. Which utilitarian states that humans derive countless direct economic benefits from nature?
a) Big utilitarian
b) Broadly utilitarian
c) Narrowly utilitarian
d) Small utilitarian
Answer: c
Clarification: The humans derive countless direct economic benefits from nature is stated by the narrowly utilitarian argument. All the world commercial things provided to us by forests are included in this. It usually deals with the benefit of humans.

9. How many species of plants contribute to the traditional medicines used by native peoples around the world?
a) 2,500
b) 2,000
c) 5,000
d) 25,000
Answer: d
Clarification: The species of plants contribute to the traditional medicines used by native peoples around the world are approximately 25,000. Some examples of traditional plants used for medicinal purposes are ginger, garlic, chamomile, tulsi, etc.

10. How many species of plants are used for the production of the drugs currently sold in the market worldwide?
a) 2 %
b) 35 %
c) 25 %
d) 5 %
Answer: c
Clarification: Almost 25 percent of plant species are used for the production of the drugs currently sold in the market worldwide. Some plants used for the production of drugs are camphor tree, coca plant, poppy, turmeric, etc.

11. Which utilitarian states that biodiversity is important for many ecosystem services that nature provides?
a) Narrowly utilitarian
b) Broadly utilitarian
c) Big utilitarian
d) Small utilitarian
Answer: b
Clarification: The biodiversity is important for many ecosystem services that nature provides is stated by the broadly utilitarian argument. It involves the conservation of biodiversity by humans because it is their moral responsibility and they derive many benefits from nature.

12. What is exploring molecular, genetic, and species-level diversity for products of economic importance called?
a) Biopiracy
b) Biofuel
c) Bioprospecting
d) Biodiversity
Answer: c
Clarification: Exploring molecular, genetic, and species-level diversity or the search for plant and animal species for products of economic importance such as medicinal drugs and other commercially valuable compounds is known as bioprospecting. The compounds explored are used in various fields such as academic, agriculture, bioremediation, pharmaceuticals, nanotechnology, industrial purposes, etc.

13. What percent of the total oxygen in the Earth’s atmosphere is released by the Amazon forest?
a) 50 %
b) 20 %
c) 40 %
d) 2 %
Answer: b
Clarification: The Amazon rainforest is the world’s largest tropical rainforest and is also known as the Amazon Jungle or Amazonia. Approximately 20 percent of the total oxygen in the Earth’s atmosphere is released by the Amazon forest by the process of photosynthesis.

14. Which one of the following is an example of conservation?
a) No use of natural resources
b) The wise use of natural resources
c) Excess use of natural resources
d) Complete use of natural resources
Answer: d
Clarification: The materials or substances occurring in nature that exist without the actions of humankind are known as natural resources. These resources can be conserved by using them wisely.

Biology Multiple Choice Questions on “Flowering Plants Reproduction – Structure of a Pollen Grain”.

1. Pollen grain protoplast is _______
a) large
b) multinucleate
c) porous
d) uninucleate
Answer: d
Clarification: Pollen grain protoplasts are uninucleate at the beginning but at the time of liberation it becomes 2 or 3 celled. Pollen grains are the male gametes. They are present inside the pollen sacs.

2. Cytoplasm of the pollen grains are rich in _______
a) starch
b) proteins
c) minerals
d) vitamins
Answer: a
Clarification: The cytoplasm is rich in starch and unsaturated oils. Unsaturated oils protect the cell or rather chromosome from radiation damage. It prevents mutation of the chromosome, ensuring the genes are protected.

3. Wall of pollen grain is called as ________
a) sporopollenin
b) sporoderm
c) stomium
d) tapetum
Answer: b
Clarification: Pollen grains are the male gametes. They’ve a wall like protective covering. Sporoderm is the wall or covering of the pollen grain. It has two layers. Exine-the outer layer and intine-the inner layer.

4. Intine is ____ in nature.
a) starchy
b) parenchymatous
c) pectocellulosic
d) epidermal
Answer: c
Clarification: Pollen grains are covered by sporoderm which constitute 2 layers, the exine (outer) and intine (inner). Intine is pectocellulosic in nature. At certain places it contains enzymatic proteins.

5. Exine is made up of ____
a) vascular strands
b) sporopollenin
c) parenchyma
d) meristematic cells
Answer: b
Clarification: Exine forms the outer layer of the pollen grain. It is made of sporopollenin. It basically helps in providing protection. Sporopollenin is chemically inert and is not broken down or degraded by enzymes.

6. Sporopollenin helps preserve pollen grains as microfossils.
a) True
b) False
Answer: a
Clarification: Sporopollenin is not affected by high temperatures, enzymes, strong acids and strong alkalis. Sporopollenin does indeed preserve the pollen grains like microfossils because of its features.

7. Exine is further differentiated into two parts.
a) True
b) False
Answer: a
Clarification: Exine possesses proteins for enzymatic and compatibility reactions. Exine is further differentiated into outer ektexine (sexine) and and inner endexine (nexine).

8. Which of the following is a part of the ektexine?
a) Baculate
b) Endothecium
c) Tapetum
d) Epidermis
Answer: a
Clarification: Ektexine is a part of the exine which forms the outer covering. Ektexine is further made up of an inner continuous foot layer, a middle discontinuous baculite layer and outermost discontinuous tectum.

9. What is palynology?
a) Study of internal morphology of pollens
b) Study of anthers
c) Study of external morphology of pollens
d) Study of young pollens
Answer: c
Clarification: Palynology is the study of the external morphology of mature pollen grains. Helps experts to identify the species, genus, family, nature, etc.

10. What is exine covered by?
a) Parenchyma
b) Paracellulose
c) Pollen
d) Pollenkit
Answer: d
Clarification: The exine is spiny to help attach itself to insects for pollination. This exine is covered by a sticky, yellow, oily covering called pollenkit. Its made up of lipids and carotenoid.

Biology Multiple Choice Questions on “The Male External Genitalia”.

1. What do the Leydig cells secrete?
a) B cells
b) Semen
c) Sperms
d) Androgen
Answer: d
Clarification: The areas on the exterior of the seminiferous tubules called interstitial spaces, contain small blood vessels and small clusters of big, polygonal cells called Leydig cells or interstitial cells. Leydig cells synthesize and secrete hormones (testicular) called androgens.

2. The growth, maintenance and functioning of secondary sex organs is maintained by the ____
a) leydig cells
b) seminal vesicles
c) posterior pituitary gland
d) testosterone
Answer: a
Clarification: The growth, maintenance and functioning of secondary sex organs (epididymis, vasa deferentia, accessory glands and penis) are under the control of testosterone hormone secreted by Leydig’s cells of testis, while those of seminiferous tubules and Leydig’s cells are controlled by Follicle Stimulating Hormone (FSH) and Interstitial Cells Stimulating Hormone (ICSH) of anterior pituitary lobe respectively.

3. Where does the vas deferens emerge from?
a) Cauda epididymis
b) Caput epididymis
c) Corset epididymis
d) Corpus epididymis
Answer: a
Clarification: A 40cm long vas deferens emerges from the cauda epididymis on each side and leaves the scrotal sac and enters the abdominal cavity through the inguinal canal.

4. Why does the end of the vas deferens dilate?
a) To enter the inguinal canal
b) For temporary storage of sperms
c) To enter the urinary bladder
d) For support
Answer: b
Clarification: The vas deferens loops over the urinary bladder where it is joined by duct from the seminal vesicle to form the ejaculatory duct. The end of the vas deferens dilates to form a spindle-like ampulla for temporary storage of sperm.

5. The free end of vas deferentia bears?
a) Ciliated cells
b) Pseudostratified columnar epithelium
c) Stereocilia
d) Leydig cells
Answer: c
Clarification: The vas deferens is lined with pseudostratified columnar epithelium. The free end of its cells also bears stereocilia. The muscular wall of the vas deferens is formed of smooth muscles, and the latter’s peristaltic contractions propel the sperms through the vas deferens

6. External opening of the urethra is called _______
a) penile urethra
b) pubic symphysis
c) prostatic urethra
d) urethral meatus
Answer: d
Clarification: External opening of the urethra is called urethral meatus. The male urethra provides a common pathway for the flow of urine called semen. It is much longer in male than in the female, measuring about 15-29 cm.

7. Prosthetic urethra carries urine and semen.
a) True
b) False
Answer: b
Clarification: The urethra includes three parts. The first part is surrounded by the prostate gland and is called the prostatic urethra which arises from the urinary bladder and carries urine only.

8. What is the second part of the urethra called?
a) Prosthetic urethra
b) Membranous urethra
c) Penile urethra
d) Urethral meatus
Answer: b
Clarification: The second part is the membranous urethra which is situated behind the lower part of the pubic symphysis. The membranous urethra is the smallest urethra.

9. Tip of the glans penis is called _______
a) ventral corpus spongiosum
b) dorsal corpora cavernosa
c) aperture
d) urinogenital aperture
Answer: d
Clarification: The penis is male genitalia (male copulatory organ). At the tip of the glans penis is the slit like opening called the external urethral orifice or urinogenital aperture.

10. The penis contains four cylindrical masses of erectile tissue.
a) False
b) True
Answer: a
Clarification: The penis contains three cylindrical masses of erectile tissue—two dorsal corpora cavernosa and one ventral corpus spongiosum. These bodies are surrounded by fibrous tissue.

Biology Multiple Choice Questions on “Reproductive Health – Population Stabilisation”.

1. The world population is ________
a) rising
b) declining
c) stabilized
d) unpredictable
Answer: a
Clarification: The global population is rising exponentially. It increased from 2 billion in 1900 to 6 billion in 2000 and has currently crossed 10 billion.

2. As of 2000 census, every 6th person in the world is an Indian.
a) True
b) False
Answer: a
Clarification: The global population in 2000 was 6 billion. Of these, Indians numbered 1 billion. Thus every 6th person should be Indian.

3. Indian population has increased significantly post _______
a) independence
b) Aryan invasion
c) globalization
d) world war 2
Answer: a
Clarification: The Indian population at the time of independence was 350 million, which soared to 1 billion by the end of 2000. Thus, there was a huge increase in population post-independence.

4. MMR stands for ________
a) maternal mortality rate
b) mother’s mortality rate
c) maternal menstruation rate
d) maternal mortality ratio
Answer: a
Clarification: MMR stands for maternal mortality rate. This refers to the death post-pregnancy. Due to increased medical facilities and improvised techniques and transport, there has been a sharp decline in MMR.

5. What does IMR stand for?
a) Infant maternity ratio
b) Infant mortality rate
c) Infant mortality ratio
d) Infant maternity rate
Answer: b
Clarification: IMR stands for Infant Mortality Ratio. It refers to the death rate of infants owing to poor health, developmental deficits, or infections. Increased medications and hygienic conditions have resulted in a decline in IMR.

6. A rapid decline in which of the following is not associated with a rise in population?
a) Death rate
b) Maternal mortality rate (MMR)
c) Infant mortality rate (IMR)
d) Fertility
Answer: d
Clarification: Highly developed medications, treatment options, quick transports, increased number of hospitals have all resulted in a decrease in death rate, MMR, IMR, and infertility. This has resulted in a longer lifespan of humans and also a rise in population.

7. What is the rate at which the population of a region increased called?
a) Birth rate
b) Population increase rate
c) Population growth rate
d) Population rise rate
Answer: c
Clarification: Population growth rate is a measure used to measure the current rate of increase in population in a given region. This can also be used to predict the population for the coming years. This helps in planning and taking appropriate steps to accommodate the new growth.

8. For country A, the population in 2000 was 1 billion. It has reached 2 billion in 2020. For country B, the population in 2000 was 160 million. It has reached 800 million in 2020. Which country will have a larger population by the end of 2030, assuming the population fold change is the same?
a) Country A will be more populous compared to Country B
b) Country B will be more populous compared to Country A
c) Both countries A and B will have the same population
d) Country A will be more populous compared to Country B
Answer: c
Clarification: Population fold change = (Final population / Initial population) / (Time period)
Therefore, the population fold change for country A = (2 billion / 1 billion) / (10 years) = 2X/year
Whereas, the population fold change for country B = (800 million / 160 million) / (10 years) = 5X/year
Now, population by 2030 = Population at 2020 * Population fold change * Time period between 2030 and 2020
Therefore, the population for country A at 2030 = 2 billion * 2X/year * 10 years = 4 billion
And the population for country B at 2030 = 800 million * 5X/year * 10 year = 4000 million = 4 billion
Hence both countries will have the same population at the end of 2030, after which the population of country B will remain higher than country A.

9. Population rise is not going to affect the food, shelter, and housing because of the advancements in technology and infrastructure.
a) True
b) False
Answer: b
Clarification: Population rise is tremendous. If significant steps are not taken, the population would be sufficient to cause problems with infrastructure, food, clothing, and any resource used by humankind.

10. What is the most effective step to reduce the population growth rate?
a) Erase humanity
b) Mass murder of newborns
c) Decrease health facilities for the poor
d) Use of contraceptive methods
Answer: d
Clarification: Contraceptive methods are promoted by various organizations for small families. These are the most comfortable and most effective methods that can be used to keep the population in check.

11. What slogan has been popularized in India for population control?
a) Hum Saath Saath hai
b) Hum Do Humare Do
c) Hum Honge Kamiyab Ek Din
d) Bharat Mata Ki Jay
Answer: b
Clarification: There has been an enormous drive across India to use contraceptive methods in order to check the population growth rate. Many advertisements and posters with the slogan of “Hum Do Humaare Do” have been used. This means, “We two, our two.”

12. Which of the following is not a step taken to keep a check on the population?
a) Marriageable age rises of females to 18 years and of males to 21 years
b) Promotion of contraceptives
c) One child norm
d) Reservation in offices for women candidates
Answer: d
Clarification: To maintain the growth rate of the Indian population, various steps have been taken by the government. An increase in the marriageable age of males and females is one such step. Also, programs like Hum Do Humaare Do and One chid norm also play a role. Contraceptives have been promoted via Television, radio, and newspapers. Reservation of women candidates at workplaces has to do with another issue of inequality and injustice.