Category: Class 11 Biology Objective Questions

Biology Written Test Questions for Medical Entrance Exams on “Mechanism of Absorption of Nutrients – 2”.

1. Where do plants obtain most of their carbon and oxygen?
a) From nitrates in the soil
b) From ammonia in the soil
c) From nitrogen in the atmosphere
d) From carbon dioxide in the atmosphere
Answer: d
Clarification: Plants obtain most of their carbon and most of their oxygen from CO₂ in the atmosphere. However, their remaining nutritional requirements are obtained from water and minerals in the soil.

2. Why can’t all minerals be passively absorbed through the roots?
a) They are present in the soil as charged particles
b) The concentration of minerals in the soil is very high
c) Minerals can never be transported
d) Roots only absorb water
Answer: a
Clarification: Unlike water, all minerals cannot be passively absorbed by the roots because the minerals are present in the soil as charged particles which cannot move across the cell membranes. Also, the concentration of the minerals in the soil is usually lower than the concentration of minerals in the roots.

3. How do most minerals enter the root?
a) Through guttation
b) Through transpiration
c) Through Active absorption
d) Through passive absorption
Answer: c
Clarification: Most minerals enter the root by active absorption into the cytoplasm of epidermal cells. This needs energy in the form of ATP. Some ions also move into the epidermal cells passively.

4. What are transport proteins?
a) They are restriction points
b) They are control points
c) They are not present in plants
d) These proteins are present in animals and absent in plants
Answer: b
Clarification: Transport proteins of endodermal cells are control points, where the plant adjusts the quantity and types of solutes that reach the xylem.

5. The root endodermis because of the layer of the cuticle can actively transport ions in all the directions.
a) True
b) False
Answer: b
Clarification: The root endodermis because of the layer of suberin can actively transport ions in one direction only. Like all the cells, the endodermal cells have many transport proteins embedded in their plasma membrane.

6. After active or passive absorption of all the mineral elements, how are minerals further transported?
a) Transported through guttation
b) Not transported at all
c) Through the transpiration stream
d) Through remobilisation
Answer: c
Clarification: After the active or passive absorption of all the mineral elements, minerals are further transported through the transpiration stream. Transpiration pull is the main mineral transporting force across the entire parts of the plants.

7. Which of the following is not a chief sink for the mineral elements?
a) Young leaves
b) Developing flower
c) Old leaves
d) Developing seeds
Answer: c
Clarification: The chief sinks for the mineral elements are the growing regions of the plant such as apical and lateral meristems, young leaves, developing flowers, fruits and seeds, and the storage organs.

8. Where does the unloading of mineral ions occur in the plants?
a) At the root endings
b) At the stem endings
c) At the root hair cells
d) At the fine vein endings
Answer: d
Clarification: Unloading of mineral ions which are required by the plants for growth and development occur at the fine vein endings through diffusion and active uptake by the plant cells.

9. Generally, from which of the following parts of the plants, the minerals are remobilised?
a) Senescent parts
b) Growing parts of the plant
c) Younger leaves
d) Dead tissues
Answer: a
Clarification: Generally, from the senescent parts of the plants mineral elements are remobilised because as those parts of the plants are going to die, there is no use of those mineral elements as no developmental processes are going to be carried out there.

10. Which of the following element is not remobilised?
a) Phosphorous
b) Sulphur
c) Nitrogen
d) Calcium
Answer: d
Clarification: Elements most readily mobilised are phosphorous, sulphur, nitrogen and potassium. Some elements that are structural components like calcium are not remobilised.

11. How do most of the nitrogen travels in the plants?
a) As ammonia
b) As nitrates
c) As inorganic ions
d) As nitrogen gas
Answer: c
Clarification: Nitrogen generally travels in the plants in the form of inorganic ions, though only some proportion of nitrogen is travelled in this form. Most of the nitrogen is being transported as organic compounds like the amino acids.

12. A small amount of exchange of materials does take place between xylem and phloem.
a) True
b) False
Answer: a
Clarification: It is true that a small amount of exchange of materials does take place between xylem and phloem because these tissues are not completely isolated from each other. Therefore, it is possible for xylem to carry organic materials while the phloem to carry inorganic nutrients.

13. Which of the following carbohydrates acts as food for the plants?
a) Glucose
b) Sucrose
c) Mannose
d) Lactose
Answer: b
Clarification: Food, primarily sucrose, is transported by the vascular tissue phloem from a source to a sink. Food in phloem sap can be transported in any required direction.

14. What is understood by the term sink in the plants?
a) The part that needs the food
b) The part that synthesises the food
c) The part that is going to die
d) The part that is going to fall
Answer: a
Clarification: Usually the source is understood to be that part of the plant which synthesises the food, i.e., the leaf, and sink, the part that needs or stores the food. But, the source and the sink may be reversed depending on the season or on the plant’s needs.

15. What is the direction of food in the phloem?
a) Bi-directional
b) Unidirectional
c) Tri-directional
d) Non-directional
Answer: a
Clarification: The direction of food in phloem is bi-directional as the leaves which synthesise food need to transport the organic materials or the food to the shoot as well to the root apex which lie in the opposite directions.

To practice Biology Written Test Questions for Medical Entrance Exams,

Biology Multiple Choice Questions on “Plants Respiration – Fermentation”.

1. Which of the following are the end products of the complete combustion of glucose?
a) CO₂ and starch
b) Fructose and lactose
c) H₂O and mannose
d) CO₂ and H₂O
Answer: d
Clarification: The complete combustion of glucose, which produces CO₂ and H₂O as end products, yields energy most of which is given out as heat. If this energy is to be useful to the cell, it should be able to utilise it to synthesise other molecules that the cell requires.

2. What is the strategy of the plants to oxidise glucose?
a) Oxidise glucose in several large steps
b) Oxidise glucose in several small steps
c) Reduce glucose in several large steps
d) Reduce glucose in several small steps
Answer: b
Clarification: The strategy that the plant cell uses is to catabolise the glucose molecule in such a way that not all the liberated energy goes out as heat. The key is to oxidise glucose, not in one step but several small steps.

3. During the process of respiration, which of the following is not released?
a) Carbon dioxide
b) Water
c) Oxygen
d) Energy
Answer: c
Clarification: During the process of respiration, oxygen is utilised and carbon-dioxide, water and energy are released as products. The combustion reaction requires oxygen.

4. What was the kind of atmosphere where the first cells on this planet lived?
a) Reducing
b) Oxidising
c) No atmosphere
d) Gold was present
Answer: a
Clarification: The first cells on this planet lived in an atmosphere that lacked oxygen. Even among present-day living organisms, we know of several organisms that are adapted to anaerobic conditions.

5. What is the breakdown of glucose to pyruvic acid known as?
a) Respiration
b) Glycolysis
c) Combustion
d) Hydrolysis
Answer: b
Clarification: In any case, all living organisms retain the enzymatic machinery to partially oxidise glucose without the help of oxygen. This breakdown of glucose to pyruvic acid is called glycolysis.

6. Glycolysis is also called an EMP pathway.
a) True
b) False
Answer: a
Clarification: The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof and J. Parnas and therefore is often referred to as the EMP pathway. The term glycolysis has originated from the Greek words meaning splitting of sugar.

7. Where does glycolysis take place?
a) Cytoplasm
b) Mitochondrial matrix
c) Plasma membrane
d) Inner mitochondrial membrane
Answer: a
Clarification: Glycolysis occurs in the cytoplasm of the cell and is present in all the living organisms. In anaerobic organisms, it is the only process in respiration.

8. Who discovered fermentation?
a) Gay Lussac
b) Louis Pasteur
c) Kepler
d) Ernst Haeckel
Answer: b
Clarification: Fermentation was discovered by Louis Pasteur. It is incomplete oxidation of glucose which is achieved under anaerobic conditions. It takes place in many prokaryotes and unicellular eukaryotes.

9. What are the final products of fermentation?
a) CO₂ and H₂O
b) CO₂ and methanol
c) H₂O and ethanol
d) CO₂ and ethanol
Answer: d
Clarification: In the process of fermentation, say by yeast, the incomplete oxidation of glucose is achieved under anaerobic conditions by sets of reactions where pyruvic acid is converted to CO₂ and ethanol.

10. Which of the following enzymes is not used under anaerobic conditions?
a) Pyruvic decarboxylase
b) Alcohol dehydrogenase
c) Lactate dehydrogenase
d) Pyruvate dehydrogenase
Answer: d
Clarification: The enzymes like pyruvic decarboxylase and alcohol dehydrogenase catalyse the steps of alcoholic fermentation. Lactate dehydrogenase is used for lactic acid fermentation.

11. Where does lactic acid fermentation take place in animal cells?
a) In the whole body
b) Sometimes in the muscles
c) Main respiratory pathway for muscles
d) In eyes
Answer: b
Clarification: In animal cells, lactic acid fermentation takes place in the muscles during the exercise, when oxygen is inadequate for cellular respiration, pyruvic acid is reduced to lactic acid by lactate dehydrogenase.

12. In lactic acid fermentation, the reducing agents are carbon dioxide and water.
a) True
b) False
Answer: b
Clarification: In lactic acid fermentation as well as alcoholic fermentation, the reducing agent is NADH+H⁺ which is re-oxidised to NAD⁺. Both these processes are hazardous, as either acid or alcohol is produced.

13. How much energy is released in lactic acid and alcohol fermentation?
a) Less than 7 per cent
b) More than 7 per cent
c) More than 50 per cent
d) More than 75 per cent
Answer: a
Clarification: In both lactic acid and alcohol fermentation not much energy is released; less than 7 per cent of the energy in glucose is released and not all of it is trapped as high energy bonds of ATP.

14. At what percentage, yeast poison themselves?
a) 4%
b) 7%
c) 13%
d) 45%
Answer: c
Clarification: Yeast poison to death when the concentration of alcohol reaches about 13 per cent. Therefore, the maximum concentration of alcohol in beverages which are naturally fermented is 13 per cent.

15. In how many ways do different cells handle pyruvic acid?
a) One
b) Two
c) Three
d) Four
Answer: c
Clarification: There are three major ways in which different cells handle pyruvic acid produced by glycolysis:
i. Lactic acid fermentation
ii. Alcoholic fermentation
iii. Aerobic Respiration

Biology Multiple Choice Questions on “Disorders in Digestive System – 1”.

1. What is the most common ailment of the alimentary canal?
a) Inflammation
b) Jaundice
c) Diarrhoea
d) Vomiting
Answer: a
Clarification: The inflammation of the alimentary canal is the most common ailment due to bacterial or viral infections. The infections are also caused by parasites of the intestine like tapeworm, roundworm, etc.

2. Which of the following is a symptom of jaundice?
a) Bile salts deposit in the liver
b) Bile salts deposit in eyes
c) Bile pigments deposit in the liver
d) Bile pigments deposit in the eyes
Answer: d
Clarification: In jaundice, the liver is affected, skin and eyes turn yellow due to the deposition of bile pigments particularly bilirubin. It is a waste material that remains in the bloodstream after iron is removed from the blood.

3. Where is the vomiting centre present in our bodies?
a) Medulla
b) Pons
c) Cerebellum
d) Hypothalamus
Answer: a
Clarification: Vomiting is the ejection of stomach contents through the mouth. This reflex action is controlled by the vomiting centre in the medulla. A feeling of nausea precedes vomiting.

4. Which of the following is the symptom of diarrhoea?
a) Limited frequency of the bowel movement
b) No bowel movement
c) Abnormal frequency of bowel movement
d) The normal frequency of bowel movement
Answer: c
Clarification: The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea. It reduces the absorption of food.

5. In constipation, there is increased liquidity of the faecal matter.
a) True
b) False
Answer: b
Clarification: In constipation, the faeces are retained within the colon as the bowel movement occurs irregularly. Increased fluidity of the faecal matter is the symptom of diarrhoea.

6. What is a bomb calorimeter?
a) Open metal chamber
b) Open brass chamber
c) The closed metal chamber filled with oxygen
d) The closed metal chamber filled with nitrogen
Answer: d
Clarification: Bomb calorimeter is a closed metal chamber which is filled with oxygen. The amount of heat liberated from the complete combustion of 1 g food in a bomb calorimeter is its gross calorific value.

7. What is the physiologic value of food?
a) The actual amount of energy combustion of 1 g of food
b) The actual amount of energy combustion of 1 Kg of food
c) The actual amount of energy combustion of 1 mg of food
d) Amount of complete combustion of 1 g food in a bomb calorimeter
Answer: a
Clarification: The actual amount of energy combustion of 1 g of food is the physiologic value of food. Physiologic value of fats and carbohydrates is 9 kcal/g and 4 kcal/g respectively.

8. What is the gross calorific value of proteins?
a) 4 kcal/g
b) 5.65 kcal/g
c) 9 kcal/g
d) 9.45 kcal/g
Answer: b
Clarification: The gross calorific value of proteins is 5.65 kcal/g while the physiologic value of proteins is 4 kcal/g. The gross calorific value of carbohydrates and fats is 4.1 kcal/g and 9.45 kcal/g respectively.

9. What is meant by absorption of food?
a) End products of digestion are thrown out of the body
b) End products of digestion are egested out of the body
c) End products of digestion are transported to the body
d) End products of digestion are passed through the intestinal mucosa
Answer: d
Clarification: Absorption is the process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph. It is carried out by passive, active or facilitated transport mechanisms.

10. Which of the following is not absorbed by simple diffusion?
a) Glucose
b) Amino acids
c) Sodium ions
d) Chloride ions
Answer: c
Clarification: Sodium ions are not absorbed by simple diffusion. Glucose, amino acids and some electrolytes like chloride ions are generally absorbed by simple diffusion. The rate or passage of these ions depends upon the concentration gradients.

11. Water is transported through a facilitated diffusion mechanism.
a) True
b) False
Answer: b
Clarification: Transport of water depends upon the osmotic gradient. However, some substances like glucose and amino acids are absorbed with the help of carrier proteins. This mechanism is called facilitated transport.

12. Which of the following is transported through active transport?
a) Sodium ions
b) Chloride ions
c) Fatty acids
d) Glycerol
Answer: a
Clarification: Active transport occurs against the concentration gradient and hence requires energy. Various nutrients like amino acids, monosaccharides like glucose and electrolytes like sodium ions are absorbed into the blood by this mechanism.

13. What are chylomicrons?
a) Very large protein-coated fat molecules
b) Very large fat coated protein molecules
c) Very small protein-coated fat molecules
d) Very small fat coated protein molecules
Answer: c
Clarification: Fatty acids and glycerol being insoluble, cannot be absorbed into the blood. They are first incorporated into micelles and then are reformed into very small protein-coated fat molecules called chylomicrons.

14. Which is the principal organ for absorption?
a) Mouth
b) Stomach
c) Small intestine
d) Large intestine
Answer: c
Clarification: The principal organ for the absorption of nutrients in the small intestine. The digestion is completed here and the final products of digestion are absorbed through the mucosa into the bloodstream and the lymph.

15. What initiates a signal for defaecation?
a) Faeces in the colon
b) Faeces in the rectum
c) Faeces in the caecum
d) Faeces in the ileum
Answer: b
Clarification: The digestive wastes, solidified into coherent faeces in the rectum initiate a neural reflex causing an urge or desire for its removal. Defaecation is a voluntary process and is carried out by mass peristaltic movements.

Biology Multiple Choice Questions on “Double Circulation”.

1. How many types of circulatory pathways are present in the animal kingdom?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: The circulatory pathways are of two major types-open circulatory systems and closed circulatory system. The closed circulatory system is considered to be more advantageous as the flow can be more precisely regulated.

2. How many chambers are present in the heart of crocodiles?
a) Two
b) Three
c) Four
d) Five
Answer: c
Clarification: All vertebrates possess a muscular chambered heart. Amphibians and the reptiles (except crocodiles) have a three-chambered heart while crocodiles, birds and mammals possess a four-chambered heart.

3. Which of the following organisms show single circulation?
a) Fishes
b) Birds
c) Mammals
d) Reptiles
Answer: a
Clarification: In fishes, the heart pumps out deoxygenated blood which is oxygenated by the gills and is supplied to the body parts where deoxygenated blood is returned to the heart. This type of circulation is known as single circulation.

4. Which of the following organisms show incomplete double circulation?
a) Birds
b) Reptiles
c) Mammals
d) Crocodiles
Answer: b
Clarification: In amphibians and reptiles, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood and is therefore known as incomplete double circulation.

5. Which of the following organisms do not show double circulation?
a) Birds
b) Mammals
c) Crocodiles
d) Reptiles
Answer: d
Clarification: In crocodiles, birds and mammals, oxygenated and deoxygenated blood is received by the left and right atrium respectively. The ventricles pump it out without any mixing up, i.e., two separate circulatory pathways, hence these animals have double circulation.

6. The heart is an ectodermally derived organ.
a) True
b) False
Answer: b
Clarification: Heart is derived from the innermost germ layer i.e., mesoderm. It is situated in the thoracic cavity, in between the two lungs and is slightly tilted to the left. Skin, nails, lens of the eye, the mouth are all derived from ectoderm.

7. Which of the following is not included in the human circulatory system?
a) Heart
b) Blood vessels
c) Blood
d) Skin
Answer: d
Clarification: Human circulatory system which is also called a blood vascular system consists of a muscular chambered heart, a network of closed branching blood vessels and blood, the fluid which is circulated.

8. The heart is covered by a membranous bag of how many walls?
a) One
b) Two
c) Three
d) It is not covered by a membranous bag
Answer: b
Clarification: Heart is protected by a double-walled membranous bag, pericardium, enclosing the pericardial fluid which acts as a shock absorber. Our heart consists of four chambers.

9. Which of the following walls separate the right and left atria?
a) Thin, intra-atrial septum
b) Thick, intra-atrial septum
c) Thick, inter-atrial septum
d) Thin, inter-atrial septum
Answer: d
Clarification: A thin, muscular wall called as the inter-atrial septum separates the right and the left atria, whereas a thick-walled, inter-ventricular septum separates the left and the right ventricles.

10. The atrium and ventricle are separated by which of the following tissues?
a) Intra-ventricular wall
b) Atrio-ventricular septum
c) Inter-ventricular septum
d) Intra-atrial septum
Answer: b
Clarification: The atrium and ventricle of the same side are separated by a thick fibrous tissue called the atrioventricular septum. However, each of these septa is provided with an opening through which the two chambers of the same sides are connected.

11. Mitral valve is present between which of the following?
a) The left atrium and left ventricle
b) The right atrium and right ventricle
c) Left and right atrium
d) Left and right ventricles
Answer: a
Clarification: A bicuspid or mitral valve guards the opening between the left atrium and the left ventricle. The opening between the right atrium and right ventricle is guarded by a tricuspid valve.

12. Each artery and vein consists of two layers.
a) True
b) False
Answer: b
Clarification: Each artery and vein consists of three layers: an inner lining of squamous endothelium, a middle layer of smooth muscle and elastic fibres and an external layer of fibrous connective tissue with collagen fibres.

13. What is the hepatic portal system?
a) The connection between the digestive tract and kidneys
b) The connection between the alimentary canal and heart
c) The connection between the alimentary canal and the brain
d) The connection between the alimentary canal and the liver
Answer: d
Clarification: A unique vascular connection exists between the digestive tract and the liver which is called a hepatic portal system. The hepatic portal vein carries blood from intestine to the liver before it is delivered to the systemic circulation.

14. Which of the following is not correctly marked in the given diagram?

a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: The correct labelling of the given diagram is as shown:

This diagram is a schematic plan of blood circulation in humans. The type of blood circulation exhibited by humans is double circulation which consists of systemic and pulmonary circulation.