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All questions of Class 10 NCERT Biology for OPSC OCS (Odisha) Exam

Largest gland in the body is –
  • a)
    Liver
  • b)
    Pancreas
  • c)
    Gastric gland
  • d)
    Adrenal
Correct answer is 'A'. Can you explain this answer?

Pooja Shah answered
Liver is the largest gland in human body. It carries out many functions such as secretion of bile juices for decomposition of lipids and vitamins, preparation of proteins for blood plasma that enables blood clotting and also detoxification.
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Which of the following is biodegradable?
  • a)
    Plastic mugs
  • b)
    Leather belts
  • c)
    Silver foil
  • d)
    Iron nails
Correct answer is option 'B'. Can you explain this answer?

Raghav Bansal answered
Leather belts are biodegradable whereas silver foils, plastic mugs and iron nails are non - biodegradable. It takes leather between 25-50 years to completely decompose.

A human zygote has :-
  • a)
    46 chromosomes
  • b)
    23 chromosomes
  • c)
    47 chromosomes
  • d)
    48 chromosome
Correct answer is option 'A'. Can you explain this answer?

Anoushka Nambiar answered
The cells from each parent that combine to form the zygote are called gametes. In humans, the male gamete is called sperm, and the female gamete is called an egg. When the gametes join they form a cell called a zygote. Human sperm and eggs contain 23 chromosomes. Human zygotes contain 46 chromosomes.

How many forms of fossil fuels are there
  • a)
    One
  • b)
    Two
  • c)
    Three
  • d)
    Four
Correct answer is option 'C'. Can you explain this answer?

Shubham Mukherjee answered
There are three major forms of fossil fuels they are coal, oil and natural gas. They formed from organic remains of plants and animals that were converted into coal, oil and natural gas by exposure to heat and the pressure of the earth’s crust over millions of years.

The minimum speed of wind which is required to run a windmill is:
  • a)
    15Km/h
  • b)
    35 Km/h
  • c)
    25Km/h
  • d)
    5 Km/h
Correct answer is option 'A'. Can you explain this answer?

Krishna Iyer answered
The minimum wind velocity for a windmill to function is 15 km per hour.
As soon as the speed of the wind becomes less than 15 kilometre per hour, the generator stops working.

Which of the following groups does not contain only biodegradable items ?
  • a)
    Grass, flowers and leather
  • b)
    Grass, wood and plastic
  • c)
    Fruit-peels, cake and lime juice
  • d)
    Cake, wood and grass
Correct answer is option 'B'. Can you explain this answer?

Amit Kumar answered
Correct Answer :- b
Explanation : A Non-Biodegradable material can be defined as a kind of substance which cannot be broken down by natural organisms and acts as a source of pollution. ... Non-biodegradable wastes are those who cannot be decomposed or dissolved by natural agents.
Plastic is a non-biodegradable substance.

Can you explain the answer of this question below:

Haemoglobin is –

  • A:

    Vitamin

  • B:

    Skin pigment

  • C:

    Blood carrier

  • D:

    Respiratory pigment

The answer is D.

Krishna Iyer answered
the hemoglobin increases the oxygen carrying capacity of blood. In humans and most other vertebrates, the most common respiratory pigment is a protein called hemoglobin.

Can you explain the answer of this question below:

Digestion of proteins starts in:

  • A:

    Mouth

  • B:

    Stomach

  • C:

    Pancreas

  • D:

    Small intestine

The answer is b.

Krishna Iyer answered
Digestion of proteins starts in stomach and is completed in intestine. The pepsin is the most important proteolytic enzyme present in stomach. It is secreted in inactive pepsinogen form which is activated on exposure to gastric acid. Pepsin breaks proteins into smaller proteoses and peptones. The peptones, proteoses are acted upon by trypsin, chymotrypsin and carboxypeptidase present in pancreatic juice. The action of these enzymes breaks peptones and proteoses into dipeptides. In intestinal juice is present aminopeptidase which finally release amino acids from dipeptides, thus finishing the digestion of proteins.

Which of the following is motile?
  • a)
    Male gamete
  • b)
    Female gamete
  • c)
    Cotyledons
  • d)
    Zygote
Correct answer is option 'A'. Can you explain this answer?

Krishna Iyer answered
Sperm motility is the ability of sperm to move efficiently. This is important in fertility because sperm need to move through the woman's reproductive tract to reach and fertilize her egg.

Which of the following is non-biodegradable?
  • a)
    Wool
  • b)
    Nylon
  • c)
    Animal bones
  • d)
    Tea leaves
Correct answer is option 'B'. Can you explain this answer?

Srishti Singh answered
Nylon plastic is the name for a long-chain, fiber forming polyamides, composing one of the largest groups of synthetic polymers. These chains are naturally very resistant to wear and tear, temperature and chemicals.so its non biodegradable.

Which is not a function of the male reproductive system in humans?
  • a)
    Nourishing the embryo
  • b)
    Producing the male gametes
  • c)
    Delivering the male gametes to the site of fertilization
  • d)
    Secreting male sex hormones
Correct answer is option 'A'. Can you explain this answer?

Harshu answered
Nourishing the embryo is the process in female reproductive system in which the embryo is nourished and protected. While the others r male reproductive system. Hope uh got that :)

Which one does not produce any digestive enzyme?
  • a)
    Pancreas
  • b)
     Liver
  • c)
    Stomach
  • d)
    none of these
Correct answer is option 'B'. Can you explain this answer?

Krishna Iyer answered
The liver doesn't secrete any enzymes. The liver secretes bile. In the presence of bile, lipase, an enzyme breaks down the fat into smaller units. Bile is stored on the gall bladder. 

The exit of waste materials from the human alimentary canal is regulated by:

  • a)
    Large intestine
  • b)
    Mouth
  • c)
    Anal sphincters
  • d)
    Urethra
Correct answer is 'C'. Can you explain this answer?
Anita Menon answered
An anal sphincter is a group of muscles at the end of the rectum that surrounds the anus and controls the release of stool, thereby maintaining continence. There are two sphincter muscles: one is internal and one is external. The external muscle helps maintain continence and keep stool in the rectum.

The main constituent of biogas is : 
  • a)
    methane
  • b)
    carbon dioxide
  • c)
    hydrogen
  • d)
    hydrogen sulphide
Correct answer is option 'A'. Can you explain this answer?

Aditi Choudhury answered
Bio-gas is an excellent fuel as it contains up to 75% methane. It burns without smoke, leaves no residue like ash in wood, charcoal and coal burning. Its heating capacity is high. Bio-gas is also used for lighting.

The importance of reproduction in organisms is because of :-
  • a)
    Formation of new individuals
  • b)
    Production of individuals with same traits
  • c)
    Production of individuals with different traits so as to being varieties in a population
  • d)
    All of the above
Correct answer is option 'D'. Can you explain this answer?

Akshara Basu answered
Reproduction is an important characteristic feature of living organisms. It is an essential life process which not only helps in survival but also helps in continuity of that race and group immortality, as by reproduction. Young ones replace the old and dying ones. These young ones feed, grow and reproduce again.

Epiglottis guards the opening of :-
  • a)
    Oesophagus
  • b)
    Eustachian tubes
  • c)
    Larynx
  • d)
    Internal nares
Correct answer is option 'C'. Can you explain this answer?

Sonam malhotra answered
The epiglottis is a flexible flap at the superior end of the larynx in the throat. It acts as a switch between the larynx and the esophagus to permit air to enter the airway to the lungs and food to pass into the gastrointestinal tract. The epiglottis also protects the body from choking on food that would normally obstruct the airway.

Copulation in human beings may result in fertilisation during (normal menstrual cycle is for 28 days)
  • a)
    4th day and 10th day
  • b)
    21th day and 28th day
  • c)
    11th day and 21st day
  • d)
    any day between 1st day and 28th day
Correct answer is option 'C'. Can you explain this answer?

Amit Sharma answered
Because fertilization of egg starts in 11 to 21 th days after that the unfertilized egg will ready to come out due to which copulation results in fertilization between 11 to 21 th days. 

 In hydroelectricity power:
  • a)
    Kinetic energy is transferred to potential
  • b)
    Potential energy is transferred to kinetic
  • c)
    Solar energy is transferred to wind energy
  • d)
    Wind energy is transferred to solar energy
Correct answer is option 'B'. Can you explain this answer?

Shubham Mukherjee answered
Hydroelectricity power stations use the kinetic energy in moving water. But the water comes from behind a dam built across a river valley. The water high up behind the dam contains potential energy.

The thick and spongy uterine wall breaks when:
  • a)
    Embryo starts developing in uterus
  • b)
    The egg is not fertilized by sperm
  • c)
    Fertilization of egg and sperm occurs
  • d)
    The egg is not released by ovary
Correct answer is option 'B'. Can you explain this answer?

Anjana Khatri answered
During your menstrual cycle, hormones make the eggs in your ovaries mature — when an egg is mature, that means it's ready to be fertilized by a sperm cell. These hormones also make the lining of your uterus thick and spongy. ... If pregnancy doesn't happen, your body doesn't need the thick lining in your uterus.

Who introduced the idea of a spontaneous generation ?
  • a)
    Aristotle
  • b)
    Empedocles
  • c)
    Anaximus
  • d)
    Aristotle
Correct answer is option 'A'. Can you explain this answer?

Krishna Iyer answered
The doctrine of spontaneous generation was coherently synthesized by Aristotle, who compiled and expanded the work of earlier natural philosophers and the various ancient explanations for the appearance of organisms, and was taken as scientific fact for two millennia.

In male reproductive system, the passage of sperms is through:
  • a)
    Scrotum
  • b)
    Seminal vesicles
  • c)
    Urinary bladder
  • d)
    Urethra
Correct answer is option 'D'. Can you explain this answer?

Vikas Kumar answered
The key male reproductive organs include the testes, epididymis, urethra, vas deferens, prostate gland, seminal vesicle, and penis. The testes are composed of coiled structures called seminiferous tubules, which are the sites of sperm production. Here, the vas deferens joins with the seminal vesicle to form the ejaculatory duct, which passes through the prostate and empties into the urethra. When ejaculation occurs, rhythmic muscle movements propel the sperm forward. Semen, also known as seminal fluid, is an organic fluid that may contain spermatozoa.M

Trophic level in an ecosystem represents
  • a)
    oxygen level
  • b)
    water level
  • c)
    energy level
  • d)
    salt level
Correct answer is option 'C'. Can you explain this answer?

Amit Sharma answered
  • Organisms occupy a place in the natural surroundings or in a community according to their feeding relationship with other organisms.
  • Based on the source of their nutrition or food, organisms occupy a specific place in the food chain that is known as their trophic level.
  • Producers belong to the first trophic level, herbivores (primary consumer) to the second and carnivores (secondary consumer) to the third.
  • The amount of energy decreases at successive trophic levels
Hence, trophic levels represent energy level as well.

Which of the following is a bile pigment?
  • a)
    Homopectin
  • b)
    Lignin
  • c)
    Bilirubin
  • d)
    Pectin
Correct answer is 'C'. Can you explain this answer?

Neha Patel answered
Bilirubin, a brownish yellow pigment of bile, secreted by the liver in vertebrates, which gives to solid waste products (feces) their characteristic colour. It is produced in bone marrow cells and in the liver as the end product of red-blood-cell (hemoglobin) breakdown. The amount of bilirubin manufactured relates directly to the quantity of blood cells destroyed. About 0.5 to 2 grams are produced daily. It has no known function and can be toxic to the fetal brain.

Which of the following is a disadvantage of most of the renewable energy sources?
  • a)
    Highly polluting         
  • b)
    High waste disposal cost
  • c)
    Unreliable supply   
  • d)
    High running cost
Correct answer is option 'C'. Can you explain this answer?

Hrishikesh Choudhary answered
Renewable energy often relies on the weather for its sources of power. Hydro generators need rain to fill dams and thereby provide electricity. Wind turbines need wind to turn the blades. Solar collectors need clear skies and sunshine.

The following light which is more effective in opening of stomata :
  • a)
    Green
  • b)
    Red
  • c)
    Blue
  • d)
    (B) and (C) both
Correct answer is option 'D'. Can you explain this answer?

Anjana Khatri answered
Among external factors, light plays predominant role in the movement of guard cells. Blue and red light are effective in both photosynthesis and stomatal opening. However, blue light is found to be more effective (relative to red light) in causing stomatal opening than in photosynthesis.

Oxygen is carried by :-
  • a)
    Leucocytes
  • b)
    Erythrocytes
  • c)
    Platelets
  • d)
    None of these
Correct answer is option 'B'. Can you explain this answer?

Pooja Shah answered
The oxygen carried by the erythrocytes can diffuse into the plasma and then through the capillary walls to reach the cells, whereas some of the carbon dioxide produced by the cells as a waste product diffuses into the capillaries to be picked up by the erythrocytes.

 Fuel used in thermal power plants is : 
  • a)
     Water
  • b)
    Uranium
  • c)
    Biomass
  • d)
    Fossil fuels
Correct answer is option 'D'. Can you explain this answer?

Hitakshi 💞💞 answered
Thermal power plants use fossil fuels like coal to produce electricity. These fossil fuels are burnt in power plants in huge amount to heat the water and by producing steam, the turbine runs which results in production of electricity. Water cannot be used as a fuel. Uranium is radioactive in nature. It is used in nuclear power plants. Biomass is used as a fuel but in biomass powered plants. So, the correct answer is option 'D'.

Can you explain the answer of this question below:

The maximum affinity of haemoglobin is with –

  • A:

    Carbon monoxide

  • B:

    Carbondioxide

  • C:

    Oxygen

  • D:

    Ammonia

The answer is A.

Naina Sharma answered
Hemoglobin in humans has a very high affinity for carbon monoxide, forming carboxyhemoglobin which is a very bright red in color. Carbon monoxide is thus problematic for humans because it has affinity higher than that of oxygen.

Fallopian tubes of female reproductive system are analogous to which part of the male reproductive system:
  • a)
    Scrotum
  • b)
    Vas Deferens
  • c)
    Prostrate gland
  • d)
    Testes
Correct answer is option 'B'. Can you explain this answer?

Arun Yadav answered
 In female reproductive system function of the fallopian tubules is to carry the ovum released by the ovaries. In the same way, In male reproductive system, function of the Vas Deferens is to carry the sperms.

Which of the following can reproduce through regeneration ?
  • a)
    Hydra
  • b)
    Planaria
  • c)
    Wall lizard
  • d)
    Both (A) and (B)
Correct answer is option 'D'. Can you explain this answer?

Akshara Basu answered
In asexual reproduction, the planarian detaches its tail end and each half regrows the lost parts by regeneration, allowing neoblasts (adult stem cells) to divide and differentiate, thus resulting in two worms. and hydra is reproduce by budding.

Puberty age in girls is between :-
  • a)
    12–18 years of age
  • b)
    10–16 years of age
  • c)
    14–20 years of age
  • d)
    15–18 years of age
Correct answer is option 'B'. Can you explain this answer?

Poorvi.m. Singh answered
Option b is correct because girls attain sexual mechurity and the menstrual cycle /menarch start in this phase,,due to adolescence

Which enzyme is responsible for digesting proteins in the stomach?
  • a)
    Ptyalin
  • b)
    Pepsin
  • c)
    Trypsin
  • d)
    HCl
Correct answer is 'B'. Can you explain this answer?

Palak Patel answered
Protein digestion begins in the stomach with the action of an enzyme called pepsin. Pepsin is the active protein-digesting enzyme of the stomach

In an ecosystem, herbivores represent
  • a)
    producers
  • b)
    primary consumers
  • c)
    secondary consumers
  • d)
    decomposers
Correct answer is option 'B'. Can you explain this answer?

Amit Sharma answered
A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. 
(i)  At the base of the food chain lie the primary producers. The primary producers are autotrophs and are most often photosynthetic organisms such as plants, algae, or cyanobacteria.
(ii) Primary consumers are the organisms that eat the primary producers. They are usually herbivores, plant-eaters, though they may be algae eaters or bacteria eaters.
(iii) Secondary consumers are the organisms that eat the primary consumers. They are generally meat-eaters called carnivores.
(iv) Tertiary consumers are the organisms that eat the secondary consumers. These are carnivore-eating carnivores, like eagles or big fish.

In a food chain, the third trophic level is always occupied by
  • a)
    carnivores
  • b)
    herbivores
  • c)
    decomposers v
  • d)
    producers
Correct answer is option 'A'. Can you explain this answer?

EduRev Class 8 answered
  • The correct answer is A: carnivores. 
  • In a food chain, trophic levels represent the position an organism occupies in the transfer of energy and nutrients.
  • The third trophic level typically consists of organisms that consume herbivores, which are at the second trophic level.
  • These organisms are known as carnivores, as they primarily feed on other animals.

A basket of vegetables contains carrot, potato, radish and tomato. Which of them represent the correct homologous structures?
  • a)
    Carrot and potato
  • b)
    Carrot and tomato
  • c)
    Radish and carrot
  • d)
    Radish and potato
Correct answer is option 'C'. Can you explain this answer?

Sonika Attitdejaatni answered
Homologous structures are those that are related by common ancestry. The common ancestry is reflected in a common structural plan. These structures might be adapted to suit different functional roles. Of the given options, potato is a storage stem, tomato is a fruit (in fact, it is a berry), radish and carrots are roots. Since both radish and carrots are roots, they have similar structural plans and are homologous.
So, the correct option is C

In aquatic plant – Hydrilla stomata are :
  • a)
    Present on leaves
  • b)
    Present on stem
  • c)
    Present on roots
  • d)
    Absent
Correct answer is option 'D'. Can you explain this answer?

Arun Yadav answered
In Hydrilla, the function of stomata is the same as in the case of terrestrial plants i.e. transpiration and exchange of gases like CO2 or O2 but the only thing is that stomata are present more on the upper surface of the floating leaves of the plants as compared to the lower side of the leaves is submerged in water.

Dark reaction of photosynthesis occurs in –
  • a)
    Grana
  • b)
    Stroma
  • c)
    Matrix
  • d)
    Cytoplasm
Correct answer is option 'B'. Can you explain this answer?

Alok Verma answered
The dark reaction occurs in the stroma of the chloroplast, where they utilize the products of the light reaction. 

Which of the following constitute a food-chain ?
  • a)
    Grass, wheat and mango
  • b)
    Grass, goat and human
  • c)
    Goat, cow and elephant
  • d)
    Grass, fish and goat
Correct answer is option 'B'. Can you explain this answer?

Vivek Rana answered
Grass, goat and human constitute a food chain. Grass is an autotroph i.e. it produces its own food. Grass is eaten by goat which is a herbivore. Human beings are omnivores (they eat both meat and plant foods) so they eat meat of goat. Hence this is a food chain.

Power plant that uses kinetic and potential energy of water to generate electricity is called
  • a)
    Nuclear Power Plant
  • b)
    Hydro electric Power plant
  • c)
    Thermal Power Plant
  • d)
    Biogas Power Plant
Correct answer is option 'B'. Can you explain this answer?

Rajiv Gupta answered
A power plant that produces electricity by using flowing water to rotate a turbine is called hydro-power plant. ... A hydroelectric power station converts the kinetic of flowing or falling water into electrical energy.

Which one is the non-renewable source of energy?
  • a)
    Ocean wave energy
  • b)
    Wind energy
  • c)
    Solar energy
  • d)
    Natural gas
Correct answer is option 'D'. Can you explain this answer?

Wahid Khan answered
Natural gas is a non-renewable fossil fuel formed from the remains of tiny sea plants and animals that died 300-400 million years ago.

Chapter doubts & questions for Class 10 NCERT Biology - 6 Months Preparation Course for OPSC 2026 is part of OPSC OCS (Odisha) exam preparation. The chapters have been prepared according to the OPSC OCS (Odisha) exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for OPSC OCS (Odisha) 2026 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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