Category: Class 11 Biology Objective Questions

Botany Objective Questions and Answers on “Long Distance Transport of Water”.

1. The movement of chloroplast in cells of Hydrilla leaf is an example of cytoplasmic streaming.
a) True
b) False
Answer: a
Clarification: Cytoplasmic streaming is the movement of cytoplasm within a plant or animal cell. It helps in symplastic movement. It is commonly seen in the movement of chloroplast in cells of Hydrilla leaf.

2. Bulk flow system occurs as a result of difference in ________
a) Height
b) Side of leaf
c) Pressure
d) Temperature
Answer: c
Clarification: Bulk flow system occurs as a result of difference in pressure. Difference in sides of leaf leads to change in amount of photosynthesis, where lower leaf carries higher amount of photosynthesis than the upper leaf. Difference in height doesn’t have any role to play as xylem vessels take water from lower height to upper height. Difference in temperature leads to change in transpiration rate.

3. The pathway of absorption of water involving system of interconnected protoplasts is _______
a) apoplastic pathway
b) symplastic pathway
c) diffusion
d) pressure flow of hypothesis
Answer: b
Clarification: Symplastic pathway consists of cytoplasm and intercellular movement through plasmodesmata. Apoplastic pathway consists of intercellular spaces and walls of the cells. Diffusion is simply the movement of water from higher concentration gradient and lower concentration gradient. Pressure flow of hypothesis is the mechanism of pathway of translocation of sugars from source to sink.

4. Water loss in its liquid phase from special openings of veins near the tip of grass blades is termed as _________
a) guttation
b) exudation
c) girdling
d) transpiration
Answer: a
Clarification: Guttation is the liquid water loss from special openings of veins of leaves. Exudation is liquid which comes out of the pores or wounds. Girdling is the experiment which proves that translocation of food occurs through phloem. Transpiration is the loss of water from leaf stomata in the form of vapors.

5. Symbiotic association of fungus with the plant root system is known as ________
a) mutualism
b) nodules
c) ureides
d) mycorrhiza
Answer: d
Clarification: Mycorrhiza is the symbiotic association of fungus with the root of the plant. Ureides is a form of nitrogen in which nodules of plants like soyabean export fixed nitrogen. Mutualism is the association where both the partners are interdependent such as plants and animals. Nodules are general associations of legume plants and bacteria.

6. Apoplastic pathway is discontinuous at _______
a) epidermis
b) cortex
c) casparian strips
d) pericycle
Answer: c
Clarification: Apoplastic pathway is carried out as:
Epidermis -> cortex-> endodermis -> pericycle -> xylem.
Casparian strips are a part of endodermis which blocks the Apoplastic pathway. It is made up of suberin.

7. Statement A: Garden hose is an example of positive hydrostatic pressure.
Statement B: Suction through straw is an example of negative hydrostatic pressure.
a) Both the statements are true
b) Both the statements are false
c) Statement A is true but Statement B is false
d) Statement B is true but Statement A is false
Answer: a
Clarification: Positive and negative hydrostatic pressure are types of bulk flow where substances move independently but still all the substances move together. It occurs due to pressure differences between two points.

8. Translocation occurs through _____
a) xylem only
b) phloem only
c) plasmodesmata
d) Vascular tissues
Answer: d
Clarification: Plasmodesmata is the connections through which cytosol movement take place. Xylem is used for water, minerals, organic nitrogen and hormones. Phloem is used for organic and inorganic solutes. Vascular tissues consist of xylem and phloem, together carrying out complete translocation.

9. The extensions of root epidermal cells which increase the surface area for absorption are called as _______
a) casparian strips
b) root hairs
c) sieve plates
d) tracheids
Answer: b
Clarification: Root hairs arise from region of maturation of the root system. They help in increasing area for absorption. Casparian strips are a part of endodermis which blocks the apoplastic pathway. Sieve plates are long columns with holes in the end walls of sieve tube cells of phloem. Tracheids are non-living parts of xylem where water enters directly.

10. The region in the figure given below represents ___________

a) apoplastic pathway
b) symplastic pathway
c) casparian strips
d) plasmodesmata
Answer: a
Clarification: Apoplastic pathway is shown in indigo color which occurs through intercellular spaces and cell walls. Symplastic pathway is through cytoplasms of the cells. Casparian strips is shown in navy blue color. Plasmodesmata is the connecting link between cells which is depicted by grey color.

To practice Botany Objective Questions and Answers,

Biology Multiple Choice Questions on “Higher Plants Photosynthesis – ATP and NADPH-1”.

1. Which of these is not a product of light reaction?
a) Oxygen
b) NADPH
c) ATP
d) NADP
Answer: d
Clarification: The process of photosynthesis has two stages-the light reaction and the dark reaction. The products of the light reaction are oxygen, ATP and NADPH. The light reaction requires light to carry out its reactions.

2. Which of these diffuse out of the chloroplast after the light reaction?
a) ATP
b) Carbon dioxide
c) Oxygen
d) NADPH
Answer: c
Clarification: The process of photosynthesis has two stages-the light reaction and the dark reaction. The products of the light reaction are oxygen, ATP and NADPH. Oxygen diffuses out of the chloroplast.

3. Which of these statements is incorrect regarding the biosynthetic phase of photosynthesis?
a) It depends on carbon dioxide and water
b) It depends on the products of light reaction
c) ATP and NADH are used
d) Sugars are synthesized
Answer: c
Clarification: The biosynthetic phase of photosynthesis depends upon the products of the light reaction, which are namely oxygen, ATP and NADPH. It leads to the synthesis of food, which are sugars.

4. Which of these scientists have contributed to photosynthesis studies?
a) Melvin Calvin
b) Hargovind Khorana
c) Gregor Mendel
d) Anthony Van Leeuwenhoek
Answer: a
Clarification: Melvin Calvin has contributed greatly to photosynthesis studies. The Calvin cycle was named after him. He first identified the compound PGA or 3-phosphoglyceric acid as a product of photosynthesis.

5. Which of these was used by Melvin Calvin for photosynthesis studies?
a) P-35
b) Radioactive C-14
c) C-13
d) Radioactive S-32
Answer: b
Clarification: Melvin Calvin used the radioactive isotope of carbon-12 or C-12, carbon-14 or C-14 in algal photosynthesis studies. This helped in determining the various steps of the Calvin cycle or pathway.

6. Who discovered the first CO₂ fixation product?
a) Anthony Van Leeuwenhoek
b) Robert Hooke
c) Melvin Calvin
d) Gregor Mendel
Answer: c
Clarification: Melvin Calvin has contributed greatly to photosynthesis studies. The Calvin cycle was named after him. He used radioactive C-14 to discover the first CO₂ fixation product of photosynthesis, PGA.

7. Which of these is a 3-carbon organic acid?
a) PGA
b) BTCA
c) Citric acid
d) Acetic acid
Answer: a
Clarification: PGA or 3-phosphoglyceric acid is a 3-carbon organic acid. Citric acid has 6 carbon atoms while acetic acid has 2 carbon atoms. PGA is a product of the carbon dioxide fixation stage of photosynthesis.

8. What is the full form of PGA?
a) 2-phosphoglyceric acid
b) 2-phosphoglutamic acid
c) 3-phosphoglutamic acid
d) 3-phosphoglyceric acid
Answer: d
Clarification: The full form of PGA is 3-phosphoglyceric acid. 3-phosphoglyceric acid is a product of the carbon dioxide fixation stage of photosynthesis. 3-phosphoglyceric acid is a 3-carbon organic acid.

9. How many carbon atoms does OAA contain?
a) 3
b) 2
c) 4
d) 1
Answer: c
Clarification: OAA or oxaloacetic acid is a 4-carbon compound. It is an organic acid. OAA or oxaloacetic acid is the first stable product of carbon dioxide fixation during photosynthesis, in some plants.

10. CO₂ assimilation during photosynthesis is of 3 types. True or false?
a) True
b) False
Answer: b
Clarification: Carbon dioxide assimilation during photosynthesis is of two types depending upon the first stable product of carbon dioxide fixation. The two types are the C₃ pathway and the C₄ pathway.

11. Which is the first product of CO₂ fixation in the C₃ pathway?
a) NADPH
b) OAA
c) ATP
d) PGA
Answer: d
Clarification: Carbon dioxide assimilation during photosynthesis is of two types depending upon the first stable product of carbon dioxide fixation. the first product of CO₂ fixation in the C₃ pathway is PGA.

12. Which is the first product of CO₂ fixation in the C₄ pathway?
a) NADPH
b) PGA
c) OAA
d) ATP
Answer: c
Clarification: Carbon dioxide assimilation during photosynthesis is of two types depending upon the first stable product of carbon dioxide fixation. the first product of CO₂ fixation in the C₄ pathway is OAA.

13. What is the primary acceptor of CO₂ in photosynthesis?
a) ATP
b) PGA
c) RuBP
d) OAA
Answer: c
Clarification: The primary acceptor of carbon dioxide in photosynthesis is RuBP or ribulose bisphosphate. Ribulose bisphosphate is a 5-carbon ketose sugar. It accepts carbon dioxide from the atmosphere.

14. Which of these compounds have 5 carbon atoms?
a) RuBP
b) OAA
c) PGA
d) ATP
Answer: a
Clarification: RuBP or Ribulose bisphosphate is a 5-carbon ketose sugar. It is the primary acceptor of carbon dioxide in photosynthesis. OAA is a 4-carbon organic acid while PGA is a 3-carbon organic acid.

15. How many carbon atoms does the primary acceptor of CO₂ in photosynthesis have?
a) 4
b) 5
c) 3
d) 2
Answer: b
Clarification: RuBP or Ribulose bisphosphate is a 5-carbon ketose sugar. It is the primary acceptor of carbon dioxide in photosynthesis. It accepts carbon dioxide from the atmosphere for the process of photosynthesis.

Botany Viva Questions and Answers on “Growth Regulators in Plants – 2”.

1. Which of the following is a gaseous hormone?
a) Ethylene
b) ABA
c) GA
d) Auxin
Answer: a
Clarification: Ethylene is a volatile gaseous hormone. GA, ABA and Auxin are acidic in nature. GA and Auxin are growth promoters while ABA is a growth inhibitor.

2. ABA is a derivative of adenine purine.
a) True
b) False
Answer: b
Clarification: ABA is a growth inhibitor. It is a derivative of carotenoids. It is functional mainly during stressful conditions. Cytokinin is a growth promoter. It is an adenine derivative (N6-furfurylamino purine). It is responsible for plant growth along with auxin hormone.

3. The hormone responsible for femaleness in cucumbers is ________
a) IAA
b) ABA
c) GA
d) Ethylene
Answer: d
Clarification: Ethylene is the hormone responsible for femaleness in cucumbers. IAA and GA induce parthenocarpy in fruits. ABA is not related to ripening of fruits.

4. Richmond Lang effect is linked to ________
a) Cytokinins
b) ABA
c) GA
d) NAA
Answer: a
Clarification: Richmond Lang effect is related to delay in senescence of mature parts of plants. It is linked to cytokinin hormone. GA and NAA also help in attaining precocious maturity. ABA promotes senescence in stressful conditions.

5. The hormone antagonistic to ABA is_______
a) IAA
b) Ethylene
c) GA
d) Kinetin
Answer: c
Clarification: GA acts antagonistically to ABA. IAA is synthetic auxin. Kinetin delays senescence. Ethylene promotes abscission of older parts.

6. The source of hormone ethylene is________
a) oats
b) ethephon
c) coconut milk
d) urine
Answer: b
Clarification: The source of hormone ethylene is ethephon. Source of auxin is oats. Source of cytokinin is coconut kernel. Auxin was first isolated from human urine.

7. The role of PGRs is a kind of intrinsic control.
a) True
b) False
Answer: a
Clarification: Plant growth is controlled by factors categorized into intrinsic control, genomic control and extrinsic control. Plant growth regulators including both promoters and inhibitors are controlled by hormones and come under intrinsic control. All the environmental factors come under extrinsic control.

8. Which of the following hormone is a stress hormone?
a) Ethylene
b) ABA
c) Auxin
d) GA
Answer: b
Clarification: ABA is a hormone which works in stressful conditions. GA acts antagonistic to ABA. Auxin leads to apical dominance. Ethylene is related to early ripening of fruits.

9. Which of the following hormone is used to induce morphogenesis in plant tissue culture?
a) Cytokinins
b) Ethylene
c) Auxin
d) ABA
Answer: a
Clarification: Cytokinins is used to induce morphogenesis in plant tissue culture. Auxin and cytokinin together in varied amounts carry out root and shoot differentiation. Ethylene leads to early ripening. ABA acts as a stress hormone.

10. The hormone responsible for enhancement of the respiration rate of fruits thereby leading to its early ripening is ________
a) Auxin
b) GA₃
c) Ethylene
d) ABA
Answer: c
Clarification: Ethylene is the hormone responsible for enhancement of the respiration rate of fruits thereby leading to its early ripening. Auxin and GA₃ induces parthenocarpy of fruits. ABA acts as a stress hormone.

To practice Botany Viva Questions and Answers,

Biology Multiple Choice Questions on “Disorders in Respiratory System”.

1. Asthma is caused due to inflammation of ______________
a) bronchi and broncioles
b) alveoli
c) trachea
d) pharynx
Answer: a
Clarification: Asthma is difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles. Because of this air passage becomes narrow also it produces extra mucous which lastly leads into difficulty in breathing.

2. Which of the following diseases can be found in workers working in a mill?
a) Emphysema
b) Occupational respiratory disorders
c) Bronchitis
d) Asthma
Answer: b
Clarification: In industries, produced dust can’t be cope up by the defense system of human body. Long and continuous exposure gives rise to inflammation leading to fibrosis and thus leading to severe lung damage.

3. Low oxygen supply to tissues is scientifically known as ________
a) bronchitis
b) emphysema
c) asphyxia
d) hypoxia
Answer: d
Clarification: When a body or a particular region of the body start depriving of oxygen due to its inadequate transport than this condition is known as hypoxia. Hypoxia may even lead into death of an individual.

4. Cigarette smoking causes______________
a) bronchitis
b) fibrosis
c) emphysema
d) asthma
Answer: c
Clarification: Emphysema is chronic disorder in which alveolar walls are damaged due to which respiratory surface is decreased. This is one of the causes of cigarette smoking.

5. Swelling and itching in bronchi is a symptom of __________
a) bronchitis
b) asthma
c) fibrosis
d) asphyxia
Answer: a
Clarification: Bronchitis is a disorder of bronchi in which there is regular swelling and itching of bronchi and is characterized by regular coughing. It may be both acute disorder or chronic disorder.

6. Emphysema is marked by ______
a) inflammation of nasal passage
b) twisting of trachea
c) filling of mucous in lungs
d) damage of alveolar walls
Answer: d
Clarification: Emphysema is a chronic disorder which is marked of damage of alveolar walls. This leads to inadequate supply of oxygen to the body parts. The most common cause found so far is cigarette smoking.

7. What changes may be observed due to increase in carbon dioxide and hydrogen ions body?
a) Decrease in breathing rate
b) Increase in breathing rate
c) No change in breathing rate
d) Increase in lung volume
Answer: b
Clarification: Chemosensitive area is highly sensitive to carbon dioxide and hydrogen ions. Increase in these substances can activate this center which in turn can signal the rhythm centre and increase breathing rate.

8. Suffocation is caused due to_______
a) increase in carbon dioxide
b) decrease in oxygen
c) decrease in hydrogen ions
d) increase in oxygen
Answer: a
Clarification: The receptors found in the body are highly sensitive to the carbon dioxide and hydrogen ions. Asphyxia is the state of suffocation due to high carbon dioxide concentration. The role of oxygen in the regulation of respiratory rhythm is quite insignificant.

9. What causes increase in respiratory rate?
a) Increase in body temperature
b) Decrease in carbon dioxide
c) Decrease in blood pressure
d) Increased oxygen
Answer: a
Clarification: The activity of respiratory centre is also affected by blood pressure and body temperature. Whenever body temperature or blood pressure is increased, respiratory center becomes more active and increase the respiratory rate.

10. Fibrosis may be caused due to_______
a) cigarette smoking
b) snorting
c) inflammation of alveoli
d) dust particles
Answer: d
Clarification: Fibrosis means proliferation of fibrous tissues. This is a kind of occupational respiratory disorder which is found mainly in workers of industries involved mainly in stone grinding. Our body do not have defense mechanism to cope up with this and it thus causes serious lung damage.

Biology Multiple Choice Questions on “Mechanism of Concentration of the Filtrate”.

1. Which of the following plays a significant role in the concentration of urine?
a) Henle’s loop and vasa recta
b) PCT and DCT
c) Glomerulus and Bowman’s capsule
d) Collecting duct and tubule
Answer: a
Clarification: Mammals can produce concentrated urine. The Henle’s loop and vasa recta present in the mammals play a significant role in the concentration of the urine.

2. What is meant by counter-current?
a) When blood flows in the opposite direction in two limbs of the Henle’s loop
b) When the blood flows in the same direction in two limbs of the Henle’s loop
c) When the blood does not flow through any of the limbs of Henle’s loop
d) When some blood flows in Henle’s loop and the other blood flows in the vasa recta
Answer: a
Clarification: As the flow of filtrate in the two limbs of Henle’s loop is in opposite directions, therefore it forms a counter current. The flow of blood through the two limbs of the vasa recta is also in a counter-current pattern.

3. What is the significance of the proximity of Henle’s loop and vasa recta?
a) Maintains osmolarity
b) Maintains the concentration of only water
c) For reabsorption of nutrients
d) No proximity at all
Answer: a
Clarification: The proximity between the Henle’s loop and vasa recta, as well as the counter-current in them, help in maintaining an increasing osmolarity towards the inner medullary interstitium.

4. What is the osmolarity of the urine in the cortex?
a) 300 mOsmol/L
b) 600 mOsmol/L
c) 900 mOsmol/L
d) 1200 mOsmol/L
Answer: a
Clarification: The osmolarity of the filtrate in the cortex is about 300 mOsmol/L while in the inner medulla it is 1200 mOsmol/L. In the inner medulla, urine is four times more concentrated than the initial filtrate.

5. The gradient of osmolarity is mainly caused by NaCl.
a) True
b) False
Answer: b
Clarification: The osmotic gradient is mainly caused by NaCl and urea. NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of the vasa recta.

6. Which of the following returns NaCl into the interstitium?
a) Ascending loop of Henle
b) Descending loop of Henle
c) Ascending portion of the vasa recta
d) Descending portion of the vasa recta
Answer: c
Clarification: NaCl is returned to the interstitium by the ascending portion of the vasa recta. Just like NaCl, small amounts of urea are also transported back to the interstitial fluid by the collecting tubule.

7. Which of the following structure make the countercurrent mechanism?
a) Henle’s loop and glomerulus
b) PCT and DCT
c) Henle’s loop and vasa recta
d) Vasa recta and collecting duct
Answer: c
Clarification: The specialized arrangement of Henle’s loop and vasa recta which enhances the transport of substances and helps in concentrating the urine is known as counter-current mechanism.

8. Which of the following is not a feature of a counter-current mechanism?
a) Helps in maintaining the concentration gradient
b) Helps in making the passage of water easier
c) Helps in concentrating the urine
d) Helps in diluting the urine
Answer: d
Clarification: Countercurrent mechanism helps to maintain a concentration gradient in the medullary interstitium. The presence of such an interstitial gradient helps in easy passage of water from the collecting tubule and therefore helps in concentrating the urine.

9. Which of the following are not involved in the monitoring of kidneys?
a) Hypothalamus
b) Heart
c) Eyes
d) JGA
Answer: c
Clarification: The functioning of the kidneys is efficiently monitored and regulated by the hormonal feedback mechanisms involving the hypothalamus, JGA, and to a certain extent, the heart.

10. Osmoreceptors in the body is not directly activated by which of the following?
a) Ionic concentration
b) Blood volume
c) Body fluid volume
d) Blood pressure
Answer: d
Clarification: Osmoreceptors in the body are directly activated by changes in the blood volume, body fluid volume, and ionic concentration. An excessive loss of fluid from the body can activate these receptors.

11. The hypothalamus releases vasopressin from the adenohypophysis.
a) True
b) False
Answer: b
Clarification: An excessive loss of body fluid stimulates the hypothalamus to release antidiuretic hormone or vasopressin from the neurohypophysis. ADH stimulates the reabsorption of water from the latter parts of the renal tubule.

12. What will happen if the blood volume increases?
a) Switch off the osmoreceptors
b) Osmoreceptors get activated
c) Osmoreceptors get permanently deactivated
d) Osmoreceptors do not play a significant role
Answer: a
Clarification: An increase in the body fluid volume or the blood volume can switch off the osmoreceptors and suppress the ADH release to complete the feedback.

13. What is ADH?
a) Vasodilator
b) Phagocytic
c) Receptor
d) Vasoconstrictor
Answer: d
Clarification: ADH affects the kidney function by its constrictory effects on the blood vessels as it is a vasoconstrictor. This causes an increase in the blood pressure which further increases the GFR.

14. Which of the following is released by JG cells when GFR falls its normal levels?
a) Renin
b) Rennin
c) Lipase
d) ADH
Answer: a
Clarification: A fall in the GFR can activate the JG cells to produce renin which converts angiotensinogen in the blood to angiotensin I and further to angiotensin II which is a powerful vasoconstrictor itself and increases the GFR.

15. Which of the following is responsible for the secretion of ANF?
a) Heart
b) Brain
c) Kidneys
d) Intestine
Answer: a
Clarification: An increase in blood flow to the atria of the heart can cause the release of Atrial Natriuretic factor or ANF which causes vasodilation and therefore decreases the blood pressure.

Biology Multiple Choice Questions on “Neural Control and Coordination – Eye-1”.

1. In which of these structures are the eyes located?
a) Glenoid cavity
b) Acetabulum
c) Pores
d) Orbits
Answer: d
Clarification: The eyes are located in two sockets present in the skull known as orbits. The orbits are bony cavities in the front part of the skull in which the eye and its appendages are accommodated and protected.

2. How many layers does the wall of the eyeball have?
a) 1
b) 2
c) 3
d) 4
Answer: c
Clarification: The wall of the eyeball has three layers. The outermost layer is known as the sclera. The middle layer is known as the choroid and it is bluish in color. The innermost layer is known as the retina.

3. What is the sclera composed of?
a) Mucoid connective tissue
b) Loose connective tissue
c) Dense connective tissue
d) Pigmented connective tissue
Answer: c
Clarification: The eyeball is surrounded by three layers. The sclera is the outermost opaque and fibrous layer that surrounds the eye. It is made up of dense connective tissue and provides protection and form.

4. What is the anterior portion of the sclera known as?
a) Cornea
b) Choroid
c) Retina
d) Iris
Answer: a
Clarification: The sclera is the outermost layer out of the three layers that surround the eyeball. The sclera is made up of dense connective tissue. The anterior portion of the sclera known as the cornea.

5. What is the middle layer of the eye known as?
a) Retina
b) Choroid
c) Cornea
d) Sclera
Answer: b
Clarification: The eyeball is surrounded by three layers, the outermost sclera, the middle choroid and the innermost retina. The choroid is rich in blood vessels to provide nourishment to the eye and is bluish.

6. The iris is a continuation of which of these structures?
a) Retina
b) Cornea
c) Ciliary body
d) Sclera
Answer: c
Clarification: The middle layer of the eye is known as the choroid layer. The choroid id thicker in the anterior portion of the eye and forms the ciliary body. The ciliary body continues forward to form the iris.

7. How many layers of neural cells does the retina possess?
a) 3
b) 2
c) 4
d) 1
Answer: a
Clarification: The retina is the innermost layer of the eyeball. It possesses three layers of neural cells which help in vision. These three layers are the ganglion cells, the bipolar cells and the photoreceptor cells.

8. Identify the part of the eye.

a) Cornea
b) Optic nerve
c) Blind spot
d) Fovea
Answer: d
Clarification: The diagram given is that of an eyeball. The indicated structure lies towards the back of the eye at its posterior pole, on the innermost layer that surrounds the eyeball. It is identified as the fovea.

9. Identify the part of the eye.

a) Ciliary bodies
b) Cornea
c) Iris
d) Lens
Answer: c
Clarification: In the given diagram of the eyeball, the indicated structure lies in the anterior part of the eye just above the lens. It is a continuation of the ciliary bodies and hence, is identified to be the iris.

10. Scotopic vision is a function of cone cells. True or false?
a) True
b) False
Answer: b
Clarification: Scotopic vision or twilight vision is a function of rod cells, while photopic vision or colored vision is a function of cone cells. The rod cells and cone cells are the photopigments present in the retina.

11. At which of these sites will you find a yellowish pigmented spot?

a) A
b) B
c) C
d) D
Answer: c
Clarification: In the given diagram of the eyeball, site C is the fovea. It is a central pit present in the yellowish pigmented spot known as the macula lutea. Visual acuity or resolution is the greatest at this spot.

12. What is retinal?
a) Aldehyde of opsin
b) Isomer of opsin
c) Aldehyde of vitamin A
d) Acid of riboflavin
Answer: c
Clarification: Retinal is an aldehyde of vitamin A and is a component of the light sensitive photopigments, along with opsin. It is present in the retina, which is the innermost layer surrounding the eye.

13. Which of these structures have a bluish appearance?
a) Sclera
b) Cornea
c) Choroid
d) Retina
Answer: c
Clarification: The eyeball is surrounded by three membranes-the outermost sclera, the middle choroid and the innermost retina. The choroid layer is rich in blood vessels and hence gives a bluish appearance.

14. The ciliary body is a part of which of these structures?
a) Choroid
b) Retina
c) Sclera
d) Macula lutea
Answer: a
Clarification: The eyeball is surrounded by three protective layers. The middle layer is known as the choroid, which is rich in blood vessels and has a bluish appearance. The ciliary body is a part of the choroid.

15. Which of these is not a characteristic of the iris?
a) It is opaque
b) It is a part of the sclera
c) It is a continuation of the ciliary bodies
d) It is pigmented
Answer: b
Clarification: The iris is not a part of the sclera, but a part of the middle layer of the eye, known as the choroid. It is opaque, pigmented and forms the colored part of the eye. The iris is a continuation of the ciliary bodies.