Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “Environmental Issues – Agro-Chemicals and their Effects”.

1. Which of the following is an agrochemical waste?
a) Mobiles
b) Pesticides
c) Sludge
d) Scrap
Answer: b
Clarification: An agricultural chemical used to help manage agriculture and farming area is known as an agrochemical. It includes insecticides, herbicides, fungicides and nematicides, antibiotics, and plant hormones. When any of the above chemicals harm the ecosystem it is said to be the agrochemical waste.

2. Which kind of pollution is caused mainly due to agrochemical waste?
a) Soil
b) Sound
c) Water
d) Air
Answer: a
Clarification: An agrochemical is a chemical used to help manage agriculture and farming area. When this chemical harms the ecosystem it is said to be the agrochemical waste. This waste mainly leads to the pollution of soil.

3. Which one of the following agro-chemical waste is added in the soil to increase the growth of plants?
a) Pesticides
b) Fertilizers
c) Water
d) Compost
Answer: b
Clarification: An agricultural chemical used to help manage agriculture and farming area is known as an agrochemical. When this chemical harms the ecosystem it is said to be the agrochemical waste. Fertilizers are the agrochemical waste is added in the soil to increase the growth of plants.

4. Which one of the following agro-chemical waste is sprayed on plants to increase their growth?
a) Fertilizers
b) Water
c) Compost
d) Pesticides
Answer: d
Clarification: A chemical used to help manage agriculture and farming area is known as an agrochemical and if this chemical does any harm to the ecosystem it is considered as agrochemical waste. Pesticides, insecticides, herbicides, fungicides, and nematicides, are the agrochemical waste that is sprayed on plants to increase their growth.

5. What is the farming called in which there is less use of chemicals and lesser production of waste?
a) Inorganic
b) Environmental
c) Organic
d) Man-made
Answer: c
Clarification: The farming having less or negligible use of chemicals and thus producing a less amount of waste is known as organic farming. It involves the cultivation of plants and rearing of animals in natural ways using biological materials (compost, manure), avoiding synthetic substances to reduce pollution.

6. What can be construed to reduce water erosion?
a) Rivers
b) Check dams
c) Hot springs
d) Oceans
Answer: b
Clarification: A small sometimes temporary, dam constructed across a drainage ditch, swale, or channel to retain water upstream, so that the water percolates into the ground and recharges the groundwater table is a check dam. It is usually constructed to reduce the erosion of soil.

7. What does the fertilizers and farm animal waste cause?
a) Air pollution
b) Industrial pollution
c) Sewage pollution
d) Agricultural water pollution
Answer: d
Clarification: Fertilizers and farm animal waste lead to agricultural water pollution. When chemicals from fertilizers and pesticides make their way into the groundwater they contaminate the only usable water source.

8. Which of the following is a cyclic and zero waste procedure?
a) Radioactive waste management
b) Oil-spill cleaning
c) Integrated organic farming
d) Reduction in thermal heat
Answer: c
Clarification: A cyclical and zero waste procedure that primarily aims at cultivating the land and raising crops in such a way that the waste products of one process is used as a nutrient for other process is known as integrated organic farming. It maximizes income in relation to area, time, and efforts.

9. What is done in integrated organic farming?
a) Less harmful waste is utilized by people
b) Waste is not generated
c) Waste products are disposed of
d) Waste products of one process are used as a nutrient for other processes
Answer: d
Clarification: A cyclic and zero waste procedure that primarily aims at cultivating the land and raising crops in such a way that the waste products of one process is used as a nutrient for other process is known as integrated organic farming. It maximizes income in relation to area, time, and efforts.

10. Which of the following can be created using crop waste?
a) Automobiles
b) Water
c) Compost
d) Plants
Answer: c
Clarification: The crop waste such as twigs, roots, husk, stem, or any organic matter that has been decomposed can form compost. It is regarded as a soil conditioner and is rich in nutrients.

Biology Multiple Choice Questions on “Flowering Plants Reproduction – Biotic Agents of Pollination”.

1. Pollination through animals is ________
a) zoophily
b) pollination
c) hydrophily
d) epihydrophily
Answer: b
Clarification: Zoophily is defined as pollination via animals. Insects are the most important animal pollinators. Birds, snails, bats, etc. also play an important role. Some lizards, lemurs, etc. also have proven to be important for pollination.

2. _______ is one of the most common families that are pollinated by animals.
a) Fabaceae
b) Euphorbiaceae
c) Asteraceae
d) Begoniaceae
Answer: c
Clarification: Zoophilous flowers are often adapted to be pollinated by particular type of animals. Bees and butterflies pollinate the maximum number of flowering plants. The two common families pollinated by them are Asteraceae and Lamiaceae.

3. Pollination by insects is called _____
a) Zoophily
b) Anemophily
c) Epihydrophily
d) Entomophily
Answer: d
Clarification: Entomophily is a common type of zoophily wherein the pollen grains of mature anthers of a flower are transferred to a mature stigma of another flower through insects like beetles, moths, butterflies, wasps, bees, etc.

4. Which of the following has attractive bracts?
a) Hibiscus
b) Bougainvillea
c) Mimosa
d) Rafflesia
Answer: b
Clarification: Other parts of the flower become showy when petals aren’t attractive. Bougainvillea is known for its showy bracts, leaves in Euphoria pulcherrima, stamens in mimosa, spathes in aroids, etc.

5. Which flower has a flytrap mechanism?
a) Viola
b) Rafflesia
c) Mimosa
d) Hydrilla
Answer: b
Clarification: Flowers attract insects in different ways. One way is by producing a smell. Pleasant odors and fragrances attract bees and butterflies. Foul smells attract flies and beetles. Rafflesia produces a foul smell which attracts flies. This is also known as the fly trap mechanism.

6. _______ produces edible pollens.
a) Rosa
b) Hibiscus
c) Viola
d) Rafflesia
Answer: a
Clarification: Edible pollens are produced by Rosa, Clematis, Magnolia, etc. Studies show that pollen grains are highly nutritive. They have even claimed to cure many health issues.

7. ______ provides safe place for insects to lay eggs.
a) Stigma
b) Nucellus
c) Amorphophallus
d) Style
Answer: c
Clarification: Some flowers provide safe place to insects for laying eggs, e.g., Yucca, Amorphophallus. Amorphophallus contains 200 species. The tallest flower belongs to Amorphophallus (six feet tall).

8. To sustain, flowers have to give rewards to insects.
a) False
b) True
Answer: b
Clarification: Nectar, pollen grains, shelter and edible floral parts and young seeds are the usual floral rewards for pollinators and juicy and nutritious fruits for seed dispersers so that insects/animals regularly visit them to feed or take shelter.

9. Pollination by birds is ____
a) Zoophily
b) Entamophily
c) Hypohydrophily
d) Ornithophily
Answer: d
Clarification: It is the mode of allogamy performed by birds. Only a few types of birds are specialised for this. They usually have small size and long beaks. Two common types of tropical pollinating birds are sun birds (Afro-Asia) and humming birds (America). Humming birds perform pollination while hovering over the flowers.

10. _____ provides nursery for moths.
a) Yucca
b) Oxalis
c) Hibiscus
d) Viola
Answer: a
Clarification: A similar relationship exists between a species of moth and the plant Yucca where both species–moth and the plant–cannot complete their life cycles without each other. The moth deposits its eggs in the locule of the ovary and the flower, in turn, gets pollinated by the moth. The larvae of the moth come out of the eggs as the seeds start developing.

11. Pollination by bats is ______
a) Ornithophily
b) Zoophily
c) Chiropterophily
d) Anmeophily
Answer: c
Clarification: It is cross pollination performed by bats. Bats are nocturnal flying mammals which can transport pollen over long distance, sometimes over 30 km. Chiropterophilous flowers are dull-coloured with strong fermenting or fruity odour, abundant nectar and pollen grains.

12. Pollination by snails is _____
a) Zoophily
b) Anemophily
c) Chiropterophily
d) Malacophily
Answer: d
Clarification: Malacophily is the pollination of plants by snails. Snails perform pollination in Arisaema (Snake or Cobra Plant) and some arum lilies.

Biology Multiple Choice Questions on “Human Reproduction – Structure of an Ovary”.

1. What cells, along with primary oocyte, make a primary follicle?
a) Granulosa cells
b) Sertoli cells
c) Secondary oocytes
d) Oogonia
Answer: a
Clarification: Oogonium initiates the first round of meiosis but ends up getting arrested at Prophase I resulting in primary oocytes. These primary oocytes are then enveloped by a single layer of granulosa cells, thus forming a primary follicle.

2. The number of primary follicles at birth and puberty is the same.
a) True
b) False
Answer: b
Clarification: Primary follicles are formed as a result of enveloping of primary oocytes by a layer of granulosa cells. These are formed during embryonic development and undergo a process of degeneration as the female matures to puberty. Hence the number of primary follicles that survive to puberty is far less, reaching only about 60,000-80,000 in each ovary.

3. In addition to granulosa cells, what additional component is added to a primary follicle to transform it into a secondary follicle?
a) Oogonia
b) Antrum
c) Theca
d) Secondary oocyte
Answer: c
Clarification: Upon undergoing meiosis, the primary follicle is formed from the oogonium. These follicles are then surrounded by a protective coating of the theca, which supports further development and division of primary oocyte. This stage of the follicle is called the secondary follicle.

4. The distinguishing characteristic of a tertiary follicle is a fluid-filled cavity called ________
a) Theca
b) Granulosa
c) Zona pellucida
d) Antrum
Answer: d
Clarification: Primary follicle is formed by the primary oocyte arrested at Prophase I and enveloped by a layer of granulosa cells. These are then enveloped by a theca resulting in a secondary follicle, which further undergoes development resulting in the formation of a fluid-filled cavity called the antrum. This mature follicle is a tertiary follicle.

5. The first round of meiosis of oogonium is completed in which follicle?
a) Graafian follicle
b) Primary follicle
c) Secondary follicle
d) Tertiary follicle
Answer: d
Clarification: The oogonium starts meiosis but is arrested at Prophase I, thereby forming primary oocyte. This oocyte then forms a primary, then secondary, and finally a tertiary follicle with the addition of granulosa cells, theca and antrum. This stage of follicle promotes further division of primary oocyte. Thus the first division of meiosis is completed in the tertiary follicle.

6. The mature follicle that holds the secondary oocyte before release from the ovary is called _________
a) graafian follicle
b) primary follicle
c) secondary follicle
d) tertiary follicle
Answer: a
Clarification: Primary oocyte completes the first round of meiosis in the tertiary oocyte, thus forming a secondary oocyte. The tertiary follicle further matures to form a Graafian follicle which ruptures and releases the secondary oocyte in the fallopian tube for fertilization.

7. What are the white remains of the Graafian follicle left after its rupture called?
a) Corpus luteum
b) Corpus callosum
c) Corpus delicti
d) Corpus handi
Answer: a
Clarification: The Graafian follicle ruptures to release the egg into the fallopian tube. The ruptured Graafian follicle results in the filling of its lumen with theca and granulosa cells, which pigment it white. This degrading follicle is hence called corpus luteum, which is then transformed into corpus albicans.

8. The ovarian stroma is composed of which two components?
a) External cortex and internal medulla
b) External medulla and internal cortex
c) External epithelium and internal medulla
d) External epithelium and internal cortex
Answer: a
Clarification: An envelope of epithelial tissue covers the ovarian stroma. The stroma is composed of two distinct parts. The outer part called cortex is composed of follicles and oocytes. The internal part is called the medulla and is composed of blood vessels, lymphatic ducts, and nerves.

9. Which of the following is not the function of the ovary?
a) Release the female gamete for fertilization
b) Produce female sex hormones
c) Provide a hostile environment for the development of the embryo
d) Protection and development of the egg
Answer: c
Clarification: The ovary is the place where the oocyte is developed from the oogonia. It houses follicles that nourish and protect eggs before they are released in the process of ovulation for fertilization. It also produces sex hormones like estrogen, which are essential for the development of secondary sexual characteristics in females. It does not hold the developing embryo. The embryo is held in the uterus.

10. Onkar was attending a Biology exam where the teacher drew a diagram of an ovary with numerous follicles. Onkar was able to identify the following four follicles in the ovary. Which of the mentioned follicles by him is incorrect?
a) Primary follicle
b) Secondary follicle
c) Tertiary follicle
d) Hair follicle
Answer: d
Clarification: Ovary has four different types of follicles, namely: Primary follicle, secondary follicle, tertiary follicle, and Graafian follicle. Hair follicles are present beneath the epithelium under the skin.

Biology Multiple Choice Questions on “Reproductive Health – Side Effects of Contraceptive Methods”.

1. Who should be consulted to discuss the pros and cons of a contraceptive?
a) Lawyers
b) Politicians
c) Astrologists
d) Doctors
Answer: d
Clarification: Contraceptive methods are difficult to select from. Based on the needs of the couple/person, a particular class of contraceptives would serve the best. To receive help in choosing the right contraceptive, they should consult a qualified doctor.

2. Contraceptives help to maintain good reproductive health.
a) True
b) False
Answer: b
Clarification: Contraceptives are agents that prevent pregnancy. These are not aimed at maintaining good reproductive health.

3. What does a contraceptive prevent?
a) fertilization
b) sterilization
c) ejaculation
d) emission
Answer: a
Clarification: Contraceptives are devised to prevent fertilization or, in some cases, pregnancy. They have different modes of action depending on the nature of the contraceptive. To use appropriate contraceptives, doctors must be consulted.

4. Which of the following is not the right reason to use a contraceptive?
a) Spacing pregnancies
b) Delaying pregnancy
c) Preventing pregnancy
d) Initiating pregnancy
Answer: d
Clarification: Contraceptives are tools/agents that are used to prevent the event of conception. Based on the needs of the individual, they can be used to prevent pregnancy or delay it or have proper spacing to suit the needs of the person and family. Contraceptives stop pregnancy; hence if a couple wants to initiate a pregnancy, a contraceptive should not be used.

5. Which of the following is a side-effect of the widespread use of contraceptives?
a) Abdominal pain
b) Bleeding
c) Nausea
d) Coma
Answer: d
Clarification: Widespread use of contraceptives can have side-effects. These can be abdominal pain, nausea, irregular menstrual bleeding, and so on.

6. Contraceptives can play a significant role to keep a check on the uncontrolled population growth.
a) True
b) False
Answer: a
Clarification: Contraceptive agents help prevent pregnancy. If appropriately used by many couples, they can be used to avoid an unwanted pregnancy. It gives families the power to plan. Thus, societies can develop and educated to ensure control in the population explosion.

Biology Multiple Choice Questions on “Chromosomal Theory of Inheritance-1”.

1. The lack of publicity of Mendel’s work was due to _______
a) lack of his ability to communicate
b) his deafness
c) lack of the availability of efficient communication methods
d) him being held captive in jail
Answer: c
Clarification: Mendel had published his work back in 1865. The communication methods were not well developed and for people to recognize the importance of his work took more than half a decade after it had been published.

2. What was the reason for the scientific community not accepting Mendel’s proposal?
a) Mendel’s factors blended, but natural changes were somewhat discrete
b) Mendel’s factors were discrete, but natural changes blended
c) Mendel’s factors were discrete, and natural changes were also discrete
d) Mendel’s factors blended and natural changes also blended
Answer: b
Clarification: Mendel’s laws of inheritance were based on the assumptions of factors/genes being discrete. However, most of the changes observed in nature exhibited the blending of characters. This led to the unacceptance of Mendel’s studies.

3. The nature exhibits ________ variation.
a) continuous
b) discontinuous
c) uniform
d) discrete
Answer: a
Clarification: The variation observed in nature is mostly continuous. This arises from the complex genetic interactions which Mendel failed to observed in his experiments on pea plants.

4. What approach used by Mendel was utterly new?
a) Mathematics to study biological phenomena
b) Crossing of plants
c) Growing garden pea plants
d) Emasculation
Answer: a
Clarification: People had performed crosses on garden pea plants before Mendel. But no one had applied a statistical and probabilistic approach to unveil the underlying phenomena. Mendel was the first to do so.

5. One of the significant drawbacks of Mendel’s work was _________
a) his study on pea plants
b) inability to show the factors being continuous
c) inability to isolate factors
d) inability to prepare proper notes
Answer: c
Clarification: Mendel’s work suggested the existence of stable and discrete factors. This was completely shocking for the contemporary scientific world. A major drawback that lied was the inability to discover the factors and prove their existence.

6. Which of the following scientists was not responsible for the rediscovery of Mendel’s work?
a) de Vries
b) Correns
c) Tschermark
d) Putin
Answer: d
Clarification: Mendel’s work was laid in papers before people could recognize it after 1900. This was achieved by the rediscovery of his work by three scientists: de Vries, Correns, and Tschermark.

7. The advent of microscopy in the 1900s allowed scientists to visualize _______
a) moon
b) cell division
c) electron
d) nucleon
Answer: b
Clarification: Microscopy came into the picture around the 1900s. This allowed scientists to visualize cells and processes like cell division.

8. What were the colored bodies observed in the nucleus during the process of division called?
a) Chromosomes
b) Genes
c) DNA
d) RNA
Answer: a
Clarification: Chromosomes means colored bodies/objects. The staining procedures allowed biologists to visualize the nucleus and chromosomes during the process of cell division.

9. Which pair of scientists to correlate chromosome movement during meiosis to Mendel’s predictions?
a) Crick and Watson
b) Newton and Einstein
c) Sutton and Boveri
d) Franklin and Wilkins
Answer: c
Clarification: Sutton and Boveri, along with other scientists, had uncovered the complete movement of chromosomes during the process of cell division. They observed that these movements correlate with Mendel’s findings.

10. What was the contribution of Theodore Boveri and Walter Sutton to Mendel’s work?
a) Rediscovery of his work
b) Challenging Mendel
c) Reperforming Mendel’s experiments in lab conditions
d) Chromosome movement correlation with Mendel’s predictions
Answer: d
Clarification: Theodore Boveri and Walter Sutton had unraveled the mechanisms underlying the chromosome movement during cell division. These movements were correlated with Mende’s laws.

11. What was the contribution of Correns, von Tschermak, and de Vries to Mendel’s work?
a) Rediscovery of his work
b) Challenging Mendel
c) Reperforming Mendel’s experiments in lab conditions
d) Chromosome movement correlation with Mendel’s predictions
Answer: a
Clarification: These three scientists helped in the rediscovery of Mendel’s work in the 1900s. Mendel’s work was published in 1865 and long forgotten.

12. Why is the chromosome behavior during cell division similar to the gene behavior?
a) Chromosome learns from gene
b) Gene learns from chromosome
c) Chromosome contains gene
d) Gene contains chromosome
Answer: c
Clarification: The chromosome is composed of many genes. Hence the behavior of gene was similar to the observed movement of the chromosome during the process of cell division.

13. What is called an equational division?
a) Mitosis
b) Meiosis
c) Mitrosis
d) Cleavage
Answer: a
Clarification: Mitosis results in the equal division of the chromosomal content of the cell. Hence it is also called equational division. The mitosis results in the production of two daughter cells from one parent cell with the exact chromosomal content as in the parent cell. This is ensured by a duplication event in the synthesis phase prior to the mitosis phase.

14. Genes occur in pairs.
a) True
b) False
Answer: a
Clarification: Genes are present on chromosomes. Each diploid cell has a set of two chromosomes. Thus, genes also occur in pairs. The pair of genes are called alleles if they code for a different protein. Usually, one copy of gene is enough to code for a functional protein. Hence the other copy is kept silent. This results in the dominant and recessive nature of the genes.

15. Chromosomes occur in pairs.
a) True
b) False
Answer: a
Clarification: Each diploid cell has a set of chromosomes. Thus, chromosomes occur in pairs. The pair of chromosomes can be either identical or differ in specific loci. If the chromosomes differ in specific loci, they are called homologous chromosomes.