Category: Class 11 Biology Objective Questions

Biology Exam Questions for Medical Entrance Exams on “Cell Cycle and Division – Meiosis-2”.

1. What is the enzyme involved in crossing over?
a) Isomerase
b) Invertase
c) Transferase
d) Recombinase
Answer: d
Clarification: Crossing over or recombination takes place during the pachytene stage of prophase I. Crossing over is an enzyme-mediated phenomenon and the enzyme involved in this process is recombinase.

2. During which stage does the synaptonemal complex dissolve?
a) Leptotene
b) Pachytene
c) Diplotene
d) Zygotene
Answer: c
Clarification: The synaptonemal complex is formed in the second stage of prophase I, that is, zygotene stage. After crossing over takes place during pachytene stage, the complex is dissolved during the diplotene stage.

3. What shape is the chiasmata?
a) S-shaped
b) Y-shaped
c) X-shaped
d) L-shaped
Answer: c
Clarification: The chiasmata is an X-shaped structure formed by the bivalents or the tetrads during prophase I of meiosis I. It occurs due to the tendency of the homologous chromosomes of a tetrad to move away from each other.

4. At what stage can one visualize chiasmata?
a) Diplotene
b) Pachytene
c) Leptotene
d) Zygotene
Answer: a
Clarification: Chiasmata is an X-shaped structure formed by the tetrad. It occurs due to the tendency of the homologous chromosomes of a tetrad to move away from each other except at the center. It occurs in the diplotene stage of prophase I.

5. During which stage does assembly of meiotic spindle take place?
a) Pachytene
b) Diakinesis
c) Metaphase I
d) Diplotene
Answer: b
Clarification: Diakinesis is the last stage of prophase I of meiosis I during which the assembly of spindle fibers takes place. Diakinesis is also characterized by the disappearance of the X-shape of chiasmata.

6. Identify the phase of meiosis.

a) Anaphase II
b) Telophase II
c) Anaphase I
d) Telophase I
Answer: c
Clarification: From the given diagram, we can observe that the chromosomes are moving towards the poles from the center. Hence, it is anaphase. Since it results in the separation of the tetrad, it is anaphase I.

7. Which of these is true about anaphase I?
a) Sister chromatids remain attached at the centromeres
b) Bivalent is unequally separated
c) Homologous chromosomes remain together
d) It takes place before diakinesis
Answer: a
Clarification: During anaphase I of meiosis, the homologous chromosomes are separated and the bivalent is hence, equally divided. It takes place after diakinesis, which is a part of prophase I. Sister chromatids are not separated.

8. Which of these stages is characterized by the disappearance of the nucleolus?
a) Zygotene
b) Pachytene
c) Diplotene
d) Diakinesis
Answer: d
Clarification: The disappearance of the nucleolus takes place during the last stage of prophase I, that is, diakinesis. This stage is also characterized by the disintegration of the nuclear membrane. It depicts transition to metaphase I.

9. During which stage of meiosis do the sister chromatids separate?
a) Telophase I
b) Anaphase I
c) Anaphase II
d) Telophase II
Answer: c
Clarification: During anaphase I, the tetrad is divided and hence the homologous chromosomes are separated. However, the sister chromatids remain attached to each other. During anaphase II, the sister chromatids are separated.

10. Nuclear membrane does not appear at the end of anaphase I. True or false?
a) True
b) False
Answer: b
Clarification: The nuclear membrane reappears at the end of anaphase I, during telophase I. Telophase I is also characterized by the appearance of the nucleolus, which was disintegrated during diakinesis.

11. Which of the following statements is false regarding interkinesis?
a) It is mostly short lived
b) It is followed by prophase II
c) It occurs after telophase I
d) Replication takes place
Answer: d
Clarification: Interkinesis is the period between meiosis I and meiosis II. It is mostly short lived and occurs after telophase I. It is followed by prophase II. However, no DNA replication takes place during this period.

12. How do chromatids reach the poles of the cells during anaphase?
a) Action of centromeres
b) Disintegration of spindle fibers
c) Shortening of microtubules
d) Movement of arms of chromatids
Answer: c
Clarification: During anaphase, the chromatids are separated and start moving towards the poles from the metaphase plate. This occurs by the shortening of the microtubules which pulls the chromatids towards the poles.

13. The stage preceding the stage during which crossing over takes place is ______
a) diplotene
b) pachytene
c) zygotene
d) leptotene
Answer: c
Clarification: Crossing over and recombination takes place during the pachytene stage of prophase I. The stage preceding this is the zygotene stage which is characterized by the formation of the synaptonemal complex.

14. Which of these statements is true about meiosis I?
a) Crossing over leads to genetic variability
b) Diplotene is short lived in vertebrates
c) Diakinesis is followed by cytokinesis
d) Chiasmata formation occurs during metaphase I
Answer: a
Clarification: Diplotene can last for years in some vertebrates, hence it is not always short lived. Diakinesis is followed by metaphase I. Chiasmata is formed during diplotene. Crossing over leads to genetic variation.

15. Identify the phase of meiosis.

a) Metaphase II
b) Metaphase I
c) Prophase II
d) Prophase I
Answer: b
Clarification: In the diagram, it is observed that the bivalents or the tetrads are aligned towards the center of the cell, that is, on the metaphase plate. Hence, the given stage is identified to be metaphase I.

To practice Biology Exam Questions for Medical Entrance Exams,

Biology MCQs for NEET Exam on “Photosynthesis Basics – 2”.

1. The following diagram represents ______

a) Joseph Priestly experiment
b) Gregor Mendel experiment
c) Engelmann experiment
d) Linnaeus experiment
Answer: a
Clarification: This shows the Joseph Priestly experiment. Here, (a) and (b) shows that when a mouse and a candle is placed in a jar without air, the mouse dies. Whereas, (c) and (d) shows that when a mint plant is placed along with the mouse and candle, we can see that the mouse is still alive. The plant restores the oxygen inside the jar.

2. During which year, Joseph Priestley discovered O₂?
a) 1774
b) 1770
c) 1884
d) 1880
Answer: a
Clarification: Joseph Priestley discovered O₂ in 1774. He found the presence of oxygen during his experiment. In a jar containing a mouse, a candle and a mint plant, he found out that the mouse was alive and the candle was lit up. This showed that the mint plant gave oxygen to the enclosed jar.

3. Photosynthesis is the basis of life on earth because ______
a) It is the main source of all food on earth
b) It helps in the release of CO₂ into the atmosphere
c) It produces new offsprings
d) It gives no energy to plants
Answer: a
Clarification: Photosynthesis is the basis of life on earth because it is the main source of all food on earth. It is also responsible for the release of oxygen into the atmosphere. It does not produce new offsprings but gives energy or glucose to the plants in the form of starch.

4. Other than CO₂ and light, which is used as the raw material for photosynthesis?
a) O₂
b) CO₂
c) H₂O
d) MnO₂
Answer: c
Clarification: The raw materials of photosynthesis are carbon dioxide and water in the presence of sunlight. And its final products are glucose, water, and oxygen. These substances are the most abundant materials on earth and provide equivalent oxygen to atmosphere.

5. Among the following, which compound does not play an important role in photosynthesis?
a) Xanthophyll
b) Anthocyanin
c) Chlorophyll
d) Phycoerythrin
Answer: b
Clarification: Anthocyanin does not play an important role in photosynthesis whereas the others have an important role. Anthocyanin main role is to provide blue, red and purple color to the plants. It also protects the plants from high temperatures and abiotic stresses.

6. What do we call the organism that does photosynthesis but does not release oxygen?
a) Green sulfur bacterium
b) Blue-green algae
c) Green algae
d) Green plants
Answer: a
Clarification: Green sulfur bacterium does photosynthesis but does not release oxygen. They are anoxygenic. They use H₂S as a substitute for water and utilize sulfide ions to form sulfur and water. No oxygen is formed.

7. In photosynthesis, the carbon dioxide is oxidized and water is reduced.
a) True
b) False
Answer: b
Clarification: It is a wrong statement. Here in photosynthesis, the carbon dioxide is reduced and water is oxidized. Carbon dioxide is reduced to glucose whereas water is oxidized to oxygen.

8. Who found out that oxygen evolved from water in photosynthesis?
a) T. W. Engelmann
b) C. Van Neil
c) R. Hill
d) Ruben and Kamen
Answer: c
Clarification: R. Hill found out that oxygen evolved from water in photosynthesis. It was believed that oxygen came from carbon dioxide. Later, Hill’s reaction showed that oxygen was produced from water.

9. What were the isotopes used, to research about photosynthesis?
a) ¹¹C and ³²P
b) ¹⁵C and ³⁵Cl
c) ¹³C and ¹⁴N
d) ¹⁴C and ¹⁸O
Answer: d
Clarification: ¹⁴C and ¹⁸O were the isotopes used to research about photosynthesis. A plant undergoing photosynthesis produces more ¹⁸O than normal oxygen. Also, ¹⁴C was used to estimate the presence of carbon atoms in the photosynthesis process.

10. Why is light energy used in photosynthesis?
a) Reduction of H₂O
b) Reduction of CO₂
c) Activation of chlorophyll
d) Oxidation of C₆H₁₂O₆
Answer: c
Clarification: Light energy is mainly used in photosynthesis for activation of chlorophyll. Chlorophyll is in an inactive state. It becomes active only in the presence of sunlight. These rays fall on chloroplast which in turn activates the chlorophyll.

11. During photosynthesis, which light is least effective?
a) Greenlight
b) Sunlight
c) Yellow light
d) Blue light
Answer: a
Clarification: Greenlight is the least effective among the following. Greenlight is reflected by green leaves, so cannot be absorbed. But blue light gives maximum absorption peak of chlorophyll and is most effective.

To practice Biology MCQs for NEET Exam,

Botany Problems on “Respiratory Quotient”.

1. Is it possible to make calculations of the net gain of ATP?
a) Not possible
b) Possible only theoretically
c) Possible only in reality
d) Sometimes possible and sometimes not
Answer: b
Clarification: Yes, it is possible to make calculations of the net gain of the ATP that is formed in the respiratory pathway by the oxidation of some suitable respiratory substrates but this can remain only a theoretical exercise as the real amount of energy released in the cell may vary.

2. Which of the following is an assumption of the respiratory balance sheet?
a) Respiration is a sequential pathway
b) Respiration does not exist
c) Energy cannot be calculated in a respiratory pathway
d) Energy is always lost in the form of heat in respiration
Answer: a
Clarification: One of the assumptions made in the respiratory balance sheet is that there is a sequential, orderly pathway functioning, with one substrate forming the next and with glycolysis, TCA cycle and ETS pathway following one after another.

3. Which of the following is not an assumption of the respiratory balance sheet?
a) NADH synthesised in glycolysis is transferred into mitochondria
b) None of the intermediates is used to synthesise other compounds
c) Respiration is a sequential pathway
d) Energy can never be stored
Answer: d
Clarification: Certain assumptions of the respiratory balance sheet include that none of the intermediates in the pathway are utilised to synthesise any other compound. Respiration is a sequential pathway and NADH synthesised in glycolysis is transferred into the mitochondria and undergoes oxidative phosphorylation.

4. All carbohydrates except for glucose can be respired in a respiratory pathway.
a) True
b) False
Answer: b
Clarification: In a respiratory pathway, only glucose is being respired, no other alternative substrates are entering in the pathway at any of the intermediary stages.

5. Do all the respiratory pathways work simultaneously?
a) No, not at all
b) They take place one after the other
c) Yes, they work simultaneously
d) Sometimes they work independently
Answer: c
Clarification: The assumptions made in the respiratory balance sheet are not valid for the living system. All pathways work simultaneously and do not take place one after another.

6. When is the ATP utilised?
a) It is utilised as and when needed
b) It is never utilised
c) It is only in the stored form
d) Only when the cell is about to replicate
Answer: a
Clarification: ATP is utilised as and when needed. Substrates enter the pathway and are withdrawn from it as and when necessary. Enzymatic rates in these pathways are controlled by multiple means.

7. How many ATP molecules are gained during aerobic respiration?
a) 2 ATP
b) 10 ATP
c) 35 ATP
d) 38 ATP
Answer: d
Clarification: Aerobic respiration involves the complete oxidation of glucose. There can be a net gain of 38 ATP molecules during aerobic respiration of one molecule of glucose.

8. How many ATP molecules are gained during fermentation?
a) 8 ATP
b) 2 ATP
c) 10 ATP
d) 4 ATP
Answer: b
Clarification: In fermentation, there is a net gain of only two molecules of ATP for each molecule of glucose degraded to pyruvic acid whereas many more molecules of ATP are generated under aerobic conditions.

9. What is the speed of oxidation of NADH in case of fermentation?
a) Vigorous
b) Very slow
c) Slow
d) Fast
Answer: c
Clarification: NADH is oxidised to NAD⁺ rather slowly in fermentation, however, the reaction is very vigorous in the case of aerobic respiration. The reducing agent in fermentation is NADH + H⁺.

10. Fermentation accounts for the complete breakdown of glucose and sucrose.
a) True
b) False
Answer: b
Clarification: Fermentation accounts for only a partial breakdown of glucose whereas in aerobic respiration it is completely degraded to CO₂ and H₂O.

11. What is the full form of RQ?
a) Respiratory Quotient
b) Reservatory Quotient
c) Reservation Q-value
d) Reservatory Q-value
Answer: a
Clarification: RQ stands for Respiratory Quotient. It is the ratio of the volume of CO₂ evolved to the volume of O₂ consumed in respiration. It is also known as the respiratory ratio.

12. On which of the following does the respiratory quotient depend?
a) The respiratory concentration of Oxygen
b) The respiratory substrate used during respiration
c) The volume of Carbon-dioxide evolved
d) Energy evolved during respiration
Answer: b
Clarification: The respiratory quotient depends upon the type of respiratory substrate used during respiration. In living organisms, respiratory substrates are often more than one.

13. What is the value of RQ in carbohydrates?
a) 0.7
b) 0.3
c) 1
d) 10
Answer: c
Clarification: When carbohydrates are used as substrates and are completely oxidised, the RQ will be 1, because equal amounts of CO₂ and O₂ are evolved and consumed respectively.

14. What is the RQ value for tripalmitin?
a) 0.9
b) 1
c) 0.3
d) 0.7
Answer: d
Clarification: When fats are used in respiration, the RQ is less than 1. For a fatty acid, tripalmitin, the ratio of the volume of carbon dioxide evolved to the volume of oxygen evolved is 0.7.

15. What is the respiratory quotient for organic acids?
a) More than 1
b) Less than zero
c) Zero
d) Less than one but greater than Zero
Answer: a
Clarification: Organic acids have R.Q value more than one. But when proteins are respiratory substrates the ratio would be about 0.9. Pure proteins or fats are never used as respiratory substrates.

To practice Botany Problems,

Biology Online Test for NEET Exam on “Human Respiratory System – 2”.

1. Where are Bowman’s glands found?
a) Olfactory epithelium
b) Cortical nephrons
c) Juxtamedullary nephrons
d) Anterior pitutary
Answer: a
Clarification: Olfactory region of nassal passage is lined by nuero sensory epithelium known as ‘Olfactory epithelium or Schneidarian membrane’. They secrete chemoreceptive substances which help in sensing smell.

2. Hyaline cartilage is not found in_________
a) thyroid cartilage
b) cricoid cartilage
c) arytenoid cartilage
d) cartilage of santorini
Answer: d
Clarification: Hyaline cartilage is glass like and found mainly in ribs, nose, larynx and trachea. Cartilage of Santorini is made up of elastic cartilage, while thyroid, cricoid, arytenoid cartilages are made up of hyaline cartilage.

3. Gaseous exchange occurs in ______
a) bronchial tree
b) respiratory tree
c) trachea
d) larynx
Answer: b
Clarification: Gaseous exchange occurs in respiratory tree, while it is absent in bronchial tree. Respiratory tree is also known as exchange zone which which includes respiratory bronchiole, alveolar duct, atria, alveolar sac and alveoli.

4. Which one of the following is secreted by Pnuemocyte type-II cells?
a) Actin
b) Lecithin
c) Mucous
d) Lysine
Answer: b
Clarification: Pnuemocyte type-I help in gaseous exchange whereas Pnuemocyte type-II secretes lecithin, which act as surfactant and prevents collapsing of alveoli by reducing the surface tension.

5. Human lungs are made up of _____
a) 2 right lobes and 3 left lobes
b) 2 right lobes and 3 left lobes
c) 3 right lobes and 2 left lobes
d) 3 right lobes and 3 left lobes
Answer: c
Clarification: Human lungs are made up of 3 right lobes and 2 left lobes. Right lung includes right anterior lobe, middle lobe, right posterior lobe. Left lung is made up of left anterior and left posterior lobe.

6. External nostrils → vestibules → nasal chambers → internal nares → naso pharynx → X → larynx → trachea. What is X?
a) Glottis
b) Alveoli
c) Atria
d) Bronchi
Answer: a
Clarification: Glottis is a part of respiratory passage and it opens into larynx. Near the glottis is a flap like structure called epiglottis. At the time of swallowing of food this flap covers the glottis to prevent the entry of food particles into it.

7. In the trachea _____ ‘C’ shaped cartilagenous rings are present.
a) 5-10
b) 10-15
c) 16-20
d) 20-25
Answer: c
Clarification: In the trachea 16-20 ‘C’ shaped cartilagenous rings are present which prevent the trachea from collapsing. These rings are c shaped in order to allow easy passage of food through oesophagus.

8. Diaphragm increases volume of thoracic cavity in _________
a) dorsal-ventral axis
b) anterior posterior axis
c) lateral regions
d) side ways
Answer: b
Clarification: Radial muscles are present in diaphgram. By the contraction in these muscles, diaphragm becomes flattened in shape, so, volume of thoracic cavity increases in anterior posterior axis.

9. Alveoli is derived from the__________
a) endoderm
b) ectoderm
c) mesoderm
d) ecto-mesoderm
Answer: a
Clarification: Endoderm is one of the primary germ layers of embryo. It gives rise to epithelium of pharynx including the eustachian tube, the tonsils, the thyroid gland, parathyroid glands, and thymus gland; the larynx, trachea, and lungs; GIT, the urinary bladder, the vagina, and urethra. Alveoli is derived from the endoderm of the embryo.

10. In which part of lungs gaseous exchange takes place in human?
a) Trachea & alveolar duct
b) Trachea & bronchi
c) Alveolar duct & alveoli
d) Alveoli & Trachea
Answer: c
Clarification: whole passage is divided into two parts one is conducting region and other is respiratory region. Conducting zone do not play any role in exchange of gases but respiratory zone does. Alveolar duct & alveoli are the part of respiratory tree and are involved in gaseous exchange.

To practice Biology Online Test for NEET Exam,

Biology Multiple Choice Questions on “Human Excretory System – 2”.

1. Which of the following structure encloses glomerulus?
a) Bowman’s capsule
b) Medullary pyramids
c) Cortex
d) Renal capsule
Answer: a
Clarification: The renal tubule, Bowman’s capsule encloses the glomerulus. Bowman’s capsule is a double-walled cup-like structure. Glomerulus along with Bowman’s capsule is called a Malpighian body. The inner wall of Bowman’s capsule consists of a special type of cells known as podocytes.

2. What is the full form of PCT?
a) Proximal Coronary Tube
b) Proximal Convoluted Tubule
c) Proximal Carotid Tube
d) Part Covering Thymus
Answer: b
Clarification: PCT stands for Proximal Convoluted Tubule. The renal corpuscle continues further to form a highly coiled network of PCT. Brush bordered cuboidal epithelium is present in PCT.

3. Which of the following is succeeded by PCT?
a) Henle’s loop
b) Glomerulus
c) DCT
d) Collecting duct
Answer: a
Clarification: The highly coiled proximal convoluted tubule leads to a hairpin shaped Henle’s loop which has a descending and an ascending limb. The ascending limb continues further to another tubule.

4. Where do the DCTs of nephrons open into?
a) PCT
b) Henle’s loop
c) Conducting duct
d) Glomerulus
Answer: c
Clarification: The ascending limb of Henle’s loop continues as another highly coiled tubular region called distal convoluted tubule (DCT). The DCTs of many nephrons open into a straight tube called collecting duct, many of which converge and open into the renal pelvis through medullary pyramids in the calyces.

5. Which of the following is not situated in the cortical region of the kidney?
a) PCT
b) DCT
c) Malpighian corpuscle
d) Loop of Henle
Answer: d
Clarification: The loop of Henle is not situated in the cortical regions of the kidney as it is that part of renal tubule which dips into the medulla. The Malpighian corpuscle, PCT, and DCT are some parts of the nephron which are situated in the cortical regions of the kidney.

6. In the majority of nephrons, the loop of Henle is too large.
a) True
b) False
Answer: b
Clarification: In the majority of nephrons, the loop of Henle is too short and extends to a very little extent into the medulla. Such nephrons are called cortical nephrons.

7. Where do the juxtamedullary nephrons dip?
a) Medullary pyramids
b) Calyces
c) Deep in the medulla
d) Renal pelvis
Answer: c
Clarification: In some of the nephrons in the kidney, the loop of Henle is very long and runs deep into the medulla. These nephrons dipping into the medullary region are known as juxtamedullary nephrons.

8. The peritubular capillaries emerge from which of the following?
a) Efferent arteriole
b) Afferent arteriole
c) Henle’s loop
d) Renal artery
Answer: a
Clarification: The peritubular capillaries emerge from the efferent arteriole which initially emerges out of glomerulus. This arteriole forms a fine capillary network around the renal tubule which is known as peritubular capillaries. These capillaries further surround the loop of Henle.

9. Which of the following runs parallel to the Henle’s loop?
a) Renal artery
b) Renal vein
c) Vasa recta
d) Ureters
Answer: c
Clarification: A minute vessel of peritubular capillaries run parallel to the Henle’s loop forming a U shaped vasa recta. Vasa recta are absent or highly reduced in cortical nephrons.

10. What does the question mark in the given figure represents?

a) Afferent arteriole
b) Efferent arteriole
c) Glomerulus
d) Bowman’s capsule
Answer: d
Clarification: The question mark represents Bowman’s capsule. The complete labelling of the given figure as shown below:

The given diagram represents a Malpighian body or a renal corpuscle.