Biology Question Paper
SECTION – A
Q.01 What is the average cell cycle span of a human cell?
The average cell cycle span of a human cell varies depending on the type of cell and its function. However, a common estimate for cells in active division is around 24 hours. This can be shorter or longer in different cell types.
Q.02 Which cells of higher organisms show anaerobic respiration?
Certain cells in higher organisms can temporarily switch to anaerobic respiration when oxygen supply is limited. The most common example is muscle cells during intense physical activity. Other examples include cells in the deeper layers of cartilage and some specialized cells in the eye.
Q.03 Does moonlight support photosynthesis? Give reason.
No, moonlight does not support photosynthesis. The intensity of moonlight is far too low to drive the photosynthetic process. Photosynthesis requires sufficient light energy, specifically in the visible light spectrum, which moonlight does not provide in adequate amounts.
Q.04 Why are cytokinins named so?
Cytokinins are named so because they promote cytokinesis, which is the division of the cytoplasm during cell division. The name literally means “cell division promoting.”
Q.05 What are the two types of agranulocytes?
Agranulocytes are a type of white blood cell (leukocyte) that lack prominent granules in their cytoplasm. The two types are:
- Lymphocytes: These include T cells, B cells, and natural killer cells, which play crucial roles in the immune system.
- Monocytes: These are phagocytic cells that differentiate into macrophages and dendritic cells, also important in immune responses.
Q.06 How many molecules of oxygen bind to one molecule of hemoglobin?
One molecule of hemoglobin can bind to four molecules of oxygen.
Q.07 What is gout?
Gout is a type of arthritis characterized by the accumulation of uric acid crystals in the joints, causing inflammation and severe pain.
Q.08 In which type of muscle tissue can you see intercalated discs?
Intercalated discs are found in cardiac muscle tissue. These specialized structures join individual cardiac muscle cells together and allow for rapid electrical and chemical communication, enabling coordinated heart contractions.
Q.09 Name the cranial meninges from outer layer to the inner layer.
The cranial meninges are the protective membranes surrounding the brain. From outer to inner layer, they are:
- Dura Mater: The tough, outermost layer.
- Arachnoid Mater: The middle layer, resembling a spider web.
- Pia Mater: The delicate, innermost layer that directly covers the brain’s surface.
Q.10 Give an example of a second messenger in the mechanism of protein hormone action.
A common example of a second messenger in protein hormone action is cyclic AMP (cAMP). Other examples include calcium ions (Ca²⁺) and inositol triphosphate (IP₃). These molecules relay signals from the cell membrane (where the hormone binds) to intracellular targets, triggering cellular responses.
Q.11 Assertion (A): Some cells undergo G0 Phase due to inactivation of cell cycle. Reason (R): Cells at this stage remain metabolically active, but no longer proliferate.
Answer: (a) If both A and R are true and R is the correct explanation of A.
Explanation: Cells enter the G0 phase (a quiescent state) when they are not actively dividing. This is often due to the inactivation of cell cycle machinery. While in G0, cells are still metabolically active, carrying out their normal functions, but they are not proliferating or preparing for division.
OR (Alternative for Q.11):
Assertion (A): In animal cells cytokinesis is achieved by the appearance of a furrow in the plasma membrane. Reason (R): In plant cells, the formation of the new cell wall begins with the formation of a simple precursor called the cell plate.
Answer: (b) If both A and R are true, but R is not the correct explanation of A.
Explanation: Both statements are true. Animal cells do use a cleavage furrow for cytokinesis, and plant cells do form a cell plate. However, these are distinct mechanisms for achieving the same outcome (cytoplasmic division). The reason doesn’t explain the assertion.
Q.12 Assertion (A): ABA acts as an anti-transpirant. Reason (R): It promotes senescence of leaf.
Answer: (b) If both A and R are true, but R is not the correct explanation of A.
Explanation: ABA (Abscisic Acid) does act as an anti-transpirant by closing stomata, reducing water loss. It also promotes senescence (aging) of leaves. However, these are separate effects of ABA, not directly causally linked.
Q.13 Assertion (A): NADH dehydrogenase is the complex II of ETS. Reason (R): Cytochrome-C acts as a mobile carrier for the transfer of electrons between complexes III and IV of ETS.
Answer: (d) If both A and R are false.
Explanation: NADH dehydrogenase is Complex I, not Complex II, of the Electron Transport System (ETS). Complex II is Succinate dehydrogenase. The statement about Cytochrome-C is true; it does act as a mobile electron carrier between Complexes III and IV.
Q.14 Assertion (A): PS-I and PS-II names are given on the basis of activity in the photosynthesis. Reason (R): During non-cyclic photophosphorylation, PS-II works first and then PS-I.
Answer: (a) If both A and R are true and R is the correct explanation of A.
Explanation: The names Photosystem I (PS-I) and Photosystem II (PS-II) are indeed based on the order of their discovery, not the order of their activity in the light-dependent reactions. However, in non-cyclic photophosphorylation, electrons do flow from PS-II to PS-I, making the reason a correct explanation for why PS-II is functionally before PS-I in that pathway.
Q.15 DIRECTION: Read the following and answer any four questions from 15(i) to 15(v) given below:
The neural and endocrine system jointly coordinate and regulate the physiological functions of the body. Certain hormones function antagonistically to each other to regulate a particular metabolism.
(i) Which pituitary hormone is secreted without involvement of a releasing hormone?
(a) TSH (b) FSH (c) oxytocin (d) prolactin
Answer: (d) prolactin
Explanation: Prolactin secretion is primarily under inhibitory control by dopamine (prolactin-inhibiting hormone). Unlike other pituitary hormones, it doesn’t require a releasing hormone for its release.
(ii) Tetraiodothyronine is
(a) T3 (b) Thyroxine (c) TSH (d) TRH
Answer: (b) Thyroxine
Explanation: Tetraiodothyronine (T4) is also known as thyroxine. T3 is triiodothyronine.
(iii) A person is having a problem with Calcium and Phosphorus metabolism. Which one of the following glands may not be functioning properly?
(a) Pancreas (b) thyroid (c) parathyroid
Answer: (c) parathyroid
Explanation: The parathyroid glands secrete parathyroid hormone (PTH), which plays a crucial role in calcium and phosphorus homeostasis.
(iv) Sertoli cells are regulated by the pituitary hormone known as
(a) LH (b) FSH (c) GH (d) prolactin
Answer: (b) FSH
Explanation: Follicle-stimulating hormone (FSH) from the pituitary stimulates Sertoli cells in the testes, which are essential for sperm development.
(v) Which hormone produces anti-inflammatory reaction and suppresses immune response in addition to its primary functions?
(a) Cortisol (b) Insulin (c) Adrenaline (d) Thyroxine
Answer: (a) Cortisol
Explanation: Cortisol, a glucocorticoid hormone from the adrenal cortex, has potent anti-inflammatory and immunosuppressive effects.
Q.16 DIRECTION: Read the following and answer any four questions from 16(i) to 16(v) given below:
Observe the given diagram of a nephron and answer the question that follows.
(Diagram as described: A nephron with labeled parts A, B, C, D, and “Malpighian body,” “Bowman’s capsule,” etc.)
Since I cannot physically draw, I will describe the diagram for you.
Imagine a kidney nephron. It starts with a cup-like structure (Bowman’s capsule) enclosing a network of capillaries (glomerulus). This is the Malpighian body. From Bowman’s capsule, a tube (PCT – proximal convoluted tubule) winds down, then forms a loop (Loop of Henle), and then winds again (DCT – distal convoluted tubule) before connecting to a collecting duct. Arteries bring blood to the glomerulus, and veins take blood away.
(i) Identify the correct pair
(a) A-Blood flowing in it is poor in waste products. (b) B-Fine branches of renal vein. (c) C-Supply blood to glomerulus. (d) D-Highly coiled structure.
Answer: (c) C-Supply blood to glomerulus.
Explanation: ‘C’ is the afferent arteriole, bringing blood to the glomerulus for filtration. ‘A’ would be the efferent arteriole (carrying blood away). ‘B’ would be near the renal vein. ‘D’ refers to the tubules, not specifically a “highly coiled structure” as all the tubules are coiled.
(ii) Renal corpuscle constitutes
(a) glomerulus and Malpighian body (b) glomerulus and Bowman’s capsule (c) Bowman’s capsule and Malpighian body (d) glomerulus only
Answer: (b) glomerulus and Bowman’s capsule
Explanation: The renal corpuscle is the combination of the glomerulus (capillaries) and Bowman’s capsule (the surrounding cup-like structure). The Malpighian body is often used synonymously but technically refers to both together.
(iii) Which of the following structures are present in the cortical region of the kidney?
(1) PCT (II) DCT (III) Collecting duct (IV) Loop of Henle
Codes
(a) Only I (b) I and II (c) I, II and III (d) III and IV
Answer: (c) I, II and III
Explanation: The renal cortex contains Bowman’s capsule, PCT, DCT, and collecting ducts. The Loop of Henle extends into the medulla (though parts of it may be in the outer medulla, which is still functionally part of the cortex).
(iv) What is the net glomerular filtration rate in an average adult?
(a) 75 ml min⁻¹ (b) 50 mL min⁻¹ (c) 125 ml min⁻¹ (d) 100 mL min⁻¹
Answer: (c) 125 ml min⁻¹
Explanation: The glomerular filtration rate (GFR) is approximately 125 mL/min in healthy adults.
(v) Which of the following is incorrect with regard to nephron?
(a) They are structural and functional units of kidney. (b) Cortical nephrons have shorter loop Henle whereas. Juxtamedullary nephrons have longer loop of Henle. (c) A human kidney has about two million nephrons. (d) DCT opens up into the collecting duct.
Answer: (c) A human kidney has about two million nephrons.
Explanation: A human kidney has approximately one million nephrons, not two million. All other statements are correct.
SECTION – B
Q.17 Given below is a diagram showing ATP synthesis during aerobic respiration, replace the symbols A, B, C, D and E by appropriate terms.
You’ll need the diagram to provide the exact terms. However, based on the general context of ATP synthesis during aerobic respiration, here’s a likely scenario:
- A: Likely refers to the inner mitochondrial membrane, where the electron transport chain is located.
- B: Could be ATP synthase, the enzyme that produces ATP.
- C: Might be ADP (adenosine diphosphate), which gets phosphorylated to ATP.
- D: Could be Pi (inorganic phosphate), required for ATP synthesis.
- E: Probably refers to ATP (adenosine triphosphate), the energy currency of the cell.
Q.18 To get a carpet like grass, lawns are mowed regularly. Is there any scientific explanation for this?
Yes, there is a scientific explanation. Regular mowing encourages lateral growth of the grass rather than vertical growth. This happens because:
- Apical Dominance: The growing tips (apical buds) of grass shoots produce hormones that suppress the growth of side shoots (lateral buds). Mowing removes these apical buds, reducing apical dominance.
- Stimulation of Lateral Growth: With apical dominance reduced, the lateral buds are stimulated to grow, resulting in a bushier, more carpet-like appearance.
- Increased Density: Regular mowing also encourages tillering (the production of new shoots from the base of the plant), which increases the density of the lawn.
Q.19 Which is the primary acceptor of CO₂ in the Calvin cycle? Name the enzyme and the product formed in this step?
- Primary CO₂ Acceptor: Ribulose-1,5-bisphosphate (RuBP)
- Enzyme: RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase)
- Product: 3-PGA (3-phosphoglycerate)
Q.20 What is the stroke volume of an adult human heart? Calculate it.
The stroke volume is the amount of blood pumped by the left ventricle of the heart in one contraction (or heartbeat).
- Normal Range: The stroke volume in a healthy adult at rest is about 70 mL (milliliters).
- Calculation: Stroke volume is calculated as the difference between the end-diastolic volume (EDV) and the end-systolic volume (ESV).
- EDV (the volume of blood in the ventricle at the end of diastole or filling) is about 120 mL.
- ESV (the volume of blood left in the ventricle at the end of systole or contraction) is about 50 mL.
- Stroke Volume = EDV – ESV = 120 mL – 50 mL = 70 mL
Q.21 Fill in the blanks at (A), (B), (C), (D) and (E) and complete the flow chart.
JG cells release (A) renin, when there is fall in (B) blood pressure or low availability of water in the body. The released chemical converts (C) angiotensinogen in the blood to angiotensin I and then to angiotensin II. Angiotensin II increases the blood pressure by constriction of (D) blood vessels (arterioles). Angiotensin II also activates the adrenal cortex to release (E) aldosterone. It causes reabsorption of Na⁺ and water, causing a rise in blood volume.
Q.22 What is the role of carbonic anhydrase in the transport of gases?
Carbonic anhydrase plays a crucial role in the transport of carbon dioxide (CO₂) in the blood. It catalyzes the reversible reaction between CO₂ and water to form carbonic acid (H₂CO₃), which then dissociates into bicarbonate ions (HCO₃⁻) and hydrogen ions (H⁺). This reaction is essential because:
- CO₂ Solubility: CO₂ is not very soluble in blood plasma. By converting it to bicarbonate, which is highly soluble, much more CO₂ can be transported in the blood.
- pH Balance: The bicarbonate buffer system also helps regulate blood pH.
Q.23 What is the limbic system? What is its function?
The limbic system is a complex network of structures located on both sides of the thalamus, immediately beneath the cerebrum. It includes the hippocampus, the amygdala, the hypothalamus, and other structures.
Functions:
- Emotions: The limbic system is heavily involved in processing and regulating emotions, such as fear, anger, and happiness.
- Memory: It plays a key role in memory formation, particularly long-term memory and spatial memory (hippocampus).
- Motivation: The limbic system is involved in motivation, reward, and pleasure.
- Behavior: It influences various behaviors, including social behavior and aggression.
OR (Alternative for Q.23):
Explain the conduction of nerve impulse as in the diagram of nerve fiber given above.
You’ll need the diagram to get the specifics. However, here’s a general explanation of nerve impulse conduction:
-
Resting Potential: The nerve fiber (axon) maintains a resting potential, a difference in electrical charge across the membrane. The inside is negative relative to the outside. This is due to the unequal distribution of ions (Na⁺ outside, K⁺ inside) and the action of the sodium-potassium pump.
-
Stimulus: A stimulus (chemical or electrical) triggers a change in the membrane’s permeability.
-
Depolarization: Sodium channels open, allowing Na⁺ to rush into the cell. This makes the inside of the cell less negative, or even positive, compared to the outside. This is called depolarization.
-
Action Potential: If the depolarization reaches a certain threshold, it triggers an action potential, a rapid change in membrane potential. This action potential travels along the nerve fiber.
-
Repolarization: After depolarization, potassium channels open, allowing K⁺ to flow out of the cell. This restores the negative charge inside the cell. This is called repolarization.
-
Refractory Period: A brief period follows during which the nerve fiber cannot be stimulated again immediately. This ensures that the impulse travels in one direction.
-
Propagation: The action potential propagates along the nerve fiber as a wave of depolarization and repolarization.
-
Synaptic Transmission: At the end of the nerve fiber, the action potential triggers the release of neurotransmitters, which transmit the signal to the next neuron or target cell (muscle, gland).
Q.24 Draw a diagram to show the structure of a thin myofilament and its components.
A thin filament in muscle is primarily composed of actin protein. Here’s a simplified representation:
Tropomyosin
-------------------------
/ Actin (G-actin units) \
/---------------------------\
/ Troponin \
---------------------------
^
|
Binding site for myosin
- Actin: The core of the thin filament consists of two strands of fibrous actin (F-actin) wound around each other in a double helix. Each F-actin strand is made up of many globular actin (G-actin) molecules.
- Tropomyosin: A long, thread-like protein that winds around the actin helix, covering the myosin-binding sites when the muscle is at rest.
- Troponin: A complex of three proteins (troponin I, troponin T, and troponin C) that are bound to the tropomyosin. Troponin controls the position of tropomyosin and regulates muscle contraction.
Q.25 Name the three zones of the adrenal cortex. Also mention the types of hormones secreted and their affect.
The adrenal cortex has three distinct zones:
-
Zona Glomerulosa: The outermost layer.
- Hormone: Mineralocorticoids (e.g., aldosterone)
- Effects: Regulate electrolyte balance (sodium and potassium) and fluid volume.
-
Zona Fasciculata: The middle layer.
- Hormone: Glucocorticoids (e.g., cortisol)
- Effects: Regulate glucose metabolism, stress response, and have anti-inflammatory effects.
-
Zona Reticularis: The innermost layer.
- Hormone: Androgens (e.g., DHEA)
- Effects: Contribute to the development of secondary sexual characteristics.
OR (Alternative for Q.25):
What is the role played by luteinizing hormones in males and females?
- Females: LH triggers ovulation (the release of an egg from the ovary) and stimulates the development of the corpus luteum (which produces progesterone).
- Males: LH stimulates the Leydig cells in the testes to produce testosterone, which is essential for sperm production and the development
of male secondary sexual characteristics.
SECTION – C
Q.26 Observe the diagram of Kreb’s cycle given below and answer the questions that follow.
(a) What are the other names for Kreb’s cycle?
Other names for the Krebs cycle include the citric acid cycle and the tricarboxylic acid (TCA) cycle.
(b) Name the compound acting as a connecting link between glycolysis and Kreb’s cycle.
Acetyl coenzyme A (acetyl CoA) acts as the connecting link. Pyruvate, the end product of glycolysis, is converted to acetyl CoA before entering the Krebs cycle.
(c) How many molecules of the following are produced in one turn of this cycle? ATP, NADH and FADH₂
Per one turn of the Krebs cycle:
- ATP: 1 molecule (directly via substrate-level phosphorylation as GTP, which usually transfers a phosphate to ADP)
- NADH: 3 molecules
- FADH₂: 1 molecule
(d) Name the enzyme present in the inner mitochondrial membrane that catalyzes the synthesis of ATP.
ATP synthase is the enzyme embedded in the inner mitochondrial membrane that catalyzes the synthesis of ATP (oxidative phosphorylation).
Q.27 Which one of the plant growth regulators would you use if you are asked to:
(a) Induce immediate stomatal closure in leaves:
Abscisic acid (ABA)
(b) ‘Bolt’ a rosette plant (rapid stem elongation before flowering):
Gibberellins
(c) Quickly ripen the green chillies:
Ethylene
(d) Increase the yield of sugarcane:
Auxins (or a combination of auxins and gibberellins)
(e) Inhibit seed germination:
Abscisic acid (ABA)
(f) Kill dicot weeds:
Auxins (specifically, synthetic auxins like 2,4-D)
Q.28 Expand PEP. Where is it produced in C₄ plants? What is its role in the biosynthetic process?
- PEP: Phosphoenolpyruvate
- Production: PEP is produced in the mesophyll cells of C₄ plants.
- Role: PEP is the primary CO₂ acceptor in C₄ photosynthesis. It combines with CO₂ to form oxaloacetate, a 4-carbon compound. This initial fixation of CO₂ occurs in the mesophyll cells and is then transferred to the bundle sheath cells where the Calvin cycle takes place. This mechanism minimizes photorespiration.
OR (Alternative for Q.28):
A cyclic process is occurring in C3 plants, which is light-dependent and needs O₂. This process does not produce energy, but rather consumes energy.
(a) Can you name the given process?
Photorespiration
(b) Is it essential or for survival?
It is not essential and is considered a wasteful process for the plant as it leads to loss of energy and carbon.
(c) What are the end products of this process?
The end products include:
- Phosphoglycolate (which is eventually converted to 3-PGA)
- CO₂ (released)
- Ammonia (NH₃)
(d) Where does it occur?
Photorespiration occurs in three organelles: chloroplasts, peroxisomes, and mitochondria.
Q.29 (a) Label the diagram and also determine the stage at which this structure is visible.
The diagram depicts a metaphase chromosome (most likely in mitosis).
- A: Sister chromatids
- B: Centromere
This structure is visible during metaphase of mitosis or meiosis II.
(b) What is interkinesis?
Interkinesis is the brief interphase between meiosis I and meiosis II. During interkinesis, there is no DNA replication.
(c) How is cytokinesis accomplished in animal cells?
Cytokinesis in animal cells occurs through the formation of a cleavage furrow. The plasma membrane pinches inward at the equator of the cell, eventually forming two separate daughter cells. This process involves the contractile ring of actin and myosin filaments.
Q.30 Represent schematically the Z scheme in the light reaction of photosynthesis. Why is it called so?
light energy
|
V
PS II
|
e-
|
Plastoquinone (PQ)
|
e-
|
Cytochrome complex
|
e-
|
Plastocyanin (PC)
|
e-
|
PS I
|
light energy
|
e-
|
Ferredoxin (Fd)
|
e-
|
NADP+ + H+
|
V
NADPH
It is called the Z scheme because the pathway of electron flow from PSII to PSI resembles the letter “Z” on its side when drawn out schematically like the above diagram.
SECTION – D
Q.31 (a) What does QRS complex represent in an ECG?
The QRS complex in an electrocardiogram (ECG) represents the ventricular depolarization and contraction (systole).
(b) What is joint diastole?
Joint diastole is the phase in the cardiac cycle when both the atria and ventricles are in diastole (relaxed). During this phase, the atrioventricular (AV) valves are open, and blood flows passively from the atria into the ventricles.
(c) Write two features that distinguish SA node and AV node.
| Feature | SA Node | AV Node |
|---|---|---|
| Location | Right atrium | Interatrial septum, near tricuspid valve |
| Function | Pacemaker of the heart | Delays the impulse from SA node |
| Discharge Rate | 70-80 impulses per minute | 40-60 impulses per minute |
(d) Name the different sounds of the heartbeat. How are they produced?
The two primary heart sounds are “lub” and “dub.”
- Lub (S1): This is the first heart sound and is caused by the closure of the atrioventricular (AV) valves (tricuspid and mitral) at the beginning of ventricular systole (contraction).
- Dub (S2): This is the second heart sound and is caused by the closure of the semilunar valves (aortic and pulmonary) at the beginning of ventricular diastole (relaxation).
OR (Alternative for Q.31):
(a) Draw a labelled diagram to show the impulse conducting system in the human heart.
Superior Vena Cava
|
Sinoatrial (SA) Node
|
Atrioventricular (AV) Node
|
Bundle of His
|
Right and Left Bundle Branches
|
Purkinje Fibers
|
Ventricles
|
Aorta
(b) How is a heart attack different from heart failure?
| Feature | Heart Attack (Myocardial Infarction) | Heart Failure (Congestive Heart Failure) |
|---|---|---|
| Cause | Blockage of coronary arteries, interrupting blood flow to the heart muscle | Inability of the heart to pump enough blood to meet the body’s needs |
| Event | Sudden and acute | Chronic and progressive |
| Primary Issue | Lack of oxygen to heart muscle | Weakened heart muscle |
Q.32 Study the graph carefully and answer the following questions.
(a) What does the graph indicate?
The graph indicates the oxygen-hemoglobin dissociation curve, showing the relationship between the partial pressure of oxygen (PO₂) and the saturation of hemoglobin with oxygen.
(b) When does the curve shift to the right?
The curve shifts to the right when there is:
- Increased temperature
- Increased carbon dioxide (CO₂) concentration
- Decreased pH (more acidic environment)
- Increased 2,3-BPG (2,3-bisphosphoglycerate) levels
(c) Does the affinity of hemoglobin for oxygen increase or decrease when the curve shifts to the right?
When the curve shifts to the right, the affinity of hemoglobin for oxygen decreases. This means that hemoglobin releases oxygen more readily to the tissues.
OR (Alternative for Q.32):
Study the figure and answer the following questions:
(a) What is being depicted by the figure?
The figure is depicting erythropoiesis, the production of red blood cells (erythrocytes).
(b) What is being shown in figure A? How is it accomplished?
Figure A shows the nucleus being ejected from the erythroblast (developing red blood cell). This is accomplished through a process of nuclear condensation and extrusion, likely involving cytoskeletal elements.
(c) What is being shown in figure B? How is it carried out?
Figure B shows the reticulocyte, an immature red blood cell, which still contains some ribosomes (reticulum). The reticulum is eventually lost, resulting in a mature erythrocyte. This maturation process involves further cellular changes and likely occurs in the bone marrow.
Q.33 Mention the name of the three stages of interphase. Explain the events of each stage.
The three stages of interphase are:
-
G1 Phase (Gap 1):
- Cell growth and synthesis of proteins and organelles required for DNA replication.
- RNA and proteins needed for cell division are synthesized.
- The cell checks for DNA damage before proceeding to the next phase.
-
S Phase (Synthesis):
- DNA replication occurs, resulting in two identical sister chromatids for each chromosome.
- Histone proteins are synthesized for packaging the DNA.
-
G2 Phase (Gap 2):
- Further cell growth and synthesis of proteins needed for cell division, particularly those required for mitosis.
- Organelles are duplicated.
- The cell checks for any errors in DNA replication before proceeding to mitosis.
OR (Alternative for Q.33):
(a) What would be the amount of DNA and chromosome in each stage of Interphase, if the initial amount is 2C and 2n, respectively?
| Stage | DNA Amount | Chromosome Number |
|---|---|---|
| G1 Phase | 2C | 2n |
| S Phase | 4C | 2n |
| G2 Phase | 4C | 2n |
(b) Distinguish anaphase of mitosis from anaphase-I of meiosis with diagrams.
| Feature | Anaphase (Mitosis) | Anaphase I (Meiosis) |
|---|---|---|
| What Separates | Sister chromatids | Homologous chromosomes |
| Movement | Chromatids move to opposite poles of the cell | Homologous chromosomes move to opposite poles of the cell |
| Reduction | No reduction in chromosome number | Reduction in chromosome number (halved) |
| Diagram | (Imagine sister chromatids separating and moving apart) | (Imagine homologous chromosomes separating and moving apart) |