Online Test: Respiration and Transport | Class 9 Biology

Question 1 of 40

In which precise compartment of the cell does glycolysis take place?

Mitochondrial matrix

Cristae

Cytoplasm

Nucleus

Explanation: Glycolysis is the initial anaerobic breakdown of glucose occurring entirely in the cytoplasm.

Question 2 of 40

What is the final electron acceptor in the mitochondrial electron transport chain?

Pyruvate

Oxygen

Carbon Dioxide

Water

Explanation: Oxygen acts as the ultimate electron acceptor, binding with protons to form water.

Question 3 of 40

What is the net yield of ATP molecules per molecule of glucose during anaerobic respiration?

38 ATP

36 ATP

4 ATP

2 ATP

Explanation: Anaerobic respiration only undergoes glycolysis, resulting in a net gain of just 2 ATP molecules.

Question 4 of 40

Which component of ATP holds the highly unstable bonds that release energy upon breaking?

Ribose sugar

Adenine base

Phosphate groups

Deoxyribose

Explanation: The high-energy anhydride bonds between terminal phosphate groups release usable energy when hydrolyzed.

Question 5 of 40

During aerobic respiration, which pathway generates the largest share of ATP molecules?

Glycolysis

Krebs Cycle

Oxidative Phosphorylation

Fermentation

Explanation: Oxidative phosphorylation utilizes electron carriers in the ETC to produce 34 out of the total 38 ATPs.

Question 6 of 40

Which structure acts as a lid to close off the larynx during swallowing?

Glottis

Epiglottis

Pharynx

Bronchus

Explanation: The epiglottis is a cartilaginous flap that seals the larynx to prevent food aspiration.

Question 7 of 40

During a deep exhalation, what action do the diaphragm and intercostal muscles perform?

Both contract

Both relax

Diaphragm contracts, muscles relax

Diaphragm relaxes, muscles contract

Explanation: Exhalation occurs when muscles relax, reducing thoracic volume and raising internal pressure.

Question 8 of 40

What is the term for the air volume that always remains in the lungs and cannot be exhaled?

Tidal Volume

Vital Capacity

Residual Volume

Total Lung Capacity

Explanation: Residual volume cannot be expelled, maintaining a base gas environment so lungs do not flatten completely.

Question 9 of 40

What is the correct chronological sequence of air passage during inhalation?

Nasal Cavity $\rightarrow$ Larynx $\rightarrow$ Pharynx $\rightarrow$ Trachea

Nasal Cavity $\rightarrow$ Pharynx $\rightarrow$ Larynx $\rightarrow$ Trachea

Pharynx $\rightarrow$ Larynx $\rightarrow$ Trachea $\rightarrow$ Bronchioles $\rightarrow$ Bronchi

Larynx $\rightarrow$ Pharynx $\rightarrow$ Trachea $\rightarrow$ Alveoli

Explanation: Air travels from nasal passage to pharynx, through the larynx voice box, into the trachea windpipe.

Question 10 of 40

What is the average Tidal Volume of a healthy adult at rest?

1200 mL

500 mL

3500 mL

6000 mL

Explanation: A normal, quiet breath moves approximately 500 mL of air in and out of the lungs.

Question 11 of 40

What basic physical mechanism governs the exchange of respiratory gases across membranes?

Active transport

Osmosis

Simple diffusion

Endocytosis

Explanation: Gas molecules cross lipid bilayers simply by diffusing down their concentration/partial pressure gradients.

Question 12 of 40

What is the typical partial pressure of oxygen ($p\text{O}_2$) in deoxygenated blood arriving at the alveoli?

104 mmHg

40 mmHg

95 mmHg

45 mmHg

Explanation: Deoxygenated blood returns with a lower $p\text{O}_2$ of about 40 mmHg before re-oxygenation.

Question 13 of 40

Which change will cause a shift of the oxyhaemoglobin dissociation curve to the right?

Decrease in temperature

Increase in pH

Decrease in $p\text{CO}_2$

Increase in hydrogen ion concentration (Lower pH)

Explanation: Increased acidity (higher $H^+$ ions) triggers a right shift, encouraging oxygen release to tissues.

Question 14 of 40

The phenomenon where hydrogen ions and $CO_2$ alter haemoglobin's affinity for $O_2$ is called...

Haldane Effect

Bohr Effect

Hamburger Phenomenon

Countercurrent Exchange

Explanation: The Bohr effect specifically describes oxygen release triggered by elevated acidity and carbon dioxide.

Question 15 of 40

Why is the alveolar respiratory membrane ideal for maximum diffusion rates?

It is thick and muscular

It has low blood supply

It is ultra-thin and highly vascularized

It contains mucus secreting cells

Explanation: Its ultra-thin layer and extensive network of capillary blood vessels minimize resistance to diffusion.

Question 16 of 40

Through which structure does the vast majority of plant transpiration take place?

Lenticels

Cuticle

Stomata

Root hairs

Explanation: Stomata handle roughly 90% of a plant's total water loss during daytime opening.

Question 17 of 40

Which environmental condition will drastically slow down the rate of transpiration?

High wind speed

Intense sunlight

High relative humidity

Elevated temperature

Explanation: Saturated atmospheric air reduces the concentration gradient, bringing evaporation to a crawl.

Question 18 of 40

The structural attraction between water molecules and the cell walls of xylem vessels is called:

Cohesion

Adhesion

Surface Tension

Guttation

Explanation: Adhesion refers to the sticking of water molecules to non-water surfaces like hydrophilic xylem walls.

Question 19 of 40

Which theory best explains the long-distance ascent of sap in tall trees?

Root Pressure Theory

Cohesion-Tension Theory

Mass Flow Hypothesis

Imbibition Theory

Explanation: The cohesion-tension theory explains how transpiration pull pulls a continuous water column up xylem tubes.

Question 20 of 40

What is a major functional benefit of transpiration for a plant?

Storing extra carbohydrates

Evaporative cooling and mineral transport

Absorbing carbon dioxide from soil

Building cell walls

Explanation: It cools leaves down in hot weather and creates suction that delivers soil nutrients upward.

Question 21 of 40

What specific electrical event does the QRS complex represent on a standard ECG?

Atrial depolarization

Ventricular depolarization

Ventricular repolarization

Atrial repolarization

Explanation: The QRS complex marks ventricular depolarization, which triggers ventricular contraction.

Question 22 of 40

What is the total duration of a single standard human cardiac cycle at rest?

0.3 seconds

0.5 seconds

0.8 seconds

1.2 seconds

Explanation: Based on an average heart rate of 72 bpm, one full cycle takes about 0.8 seconds.

Question 23 of 40

Which instrument is used by medical professionals to measure arterial blood pressure?

Stethoscope

Barometer

Sphygmomanometer

ECG Machine

Explanation: A sphygmomanometer uses an inflatable cuff to measure systolic and diastolic pressures in mmHg.

Question 24 of 40

During which phase of the cardiac cycle do the heart chambers relax and fill with blood?

Systole

Diastole

Depolarization

Isovolumetric contraction

Explanation: Diastole is the relaxation phase when blood fills the chambers.

Question 25 of 40

What does the number 80 represent in a standard blood pressure reading of 120/80 mmHg?

Systolic pressure

Pulse pressure

Diastolic pressure

Mean arterial pressure

Explanation: The lower number represents diastolic pressure, the baseline pressure in arteries between heartbeats.

Question 26 of 40

Which blood component is primarily responsible for the transport of oxygen?

Platelets

Plasma Albumin

Red Blood Cells

Leucocytes

Explanation: Erythrocytes (RBCs) contain haemoglobin, which binds and carries oxygen molecules.

Question 27 of 40

What is the main structural characteristic of a mature mammalian Red Blood Cell?

Multilobed nucleus

Nucleus and many mitochondria

Lack of a nucleus and biconcave shape

Spherical with long pseudopodia

Explanation: Mature RBCs lack a nucleus to maximize space for haemoglobin and oxygen transport.

Question 28 of 40

Which plasma protein plays a direct role in blood coagulation?

Albumin

Fibrinogen

Alpha globulin

Insulin

Explanation: Fibrinogen is converted into insoluble fibrin strands to form a stable blood clot over wounds.

Question 29 of 40

Megakaryocytes in the bone marrow fragment into which formed elements of blood?

Monocytes

Erythrocytes

Blood Platelets

T-Lymphocytes

Explanation: Platelets are cell fragments derived from the cytoplasm of large megakaryocytes.

Question 30 of 40

Which type of white blood cell is specialized to produce antibodies?

Neutrophils

Basophils

Lymphocytes

Eosinophils

Explanation: B-lymphocytes produce specific antibodies that target and neutralize foreign antigens.

Question 31 of 40

Which antigens are present on the surface of red blood cells in a person with Type O+ blood?

A and B antigens

Rh antigen only

A, B, and Rh antigens

No antigens at all

Explanation: Type O blood lacks A and B antigens, but the "+" sign indicates the presence of the Rh antigen.

Question 32 of 40

Who is considered the universal donor for blood transfusions?

AB positive (AB+)

O positive (O+)

AB negative (AB-)

O negative (O-)

Explanation: O negative blood lacks A, B, and Rh surface antigens, meaning it will not cause an immune reaction in recipients.

Question 33 of 40

What dangerous reaction happens when incompatible blood groups are mixed during a transfusion?

Hemofiltration

Agglutination

Coagulation

Phagocytosis

Explanation: Agglutination is the clumping of red blood cells caused by antibodies binding to foreign surface antigens.

Question 34 of 40

A person with Type A blood naturally carries which antibodies in their blood plasma?

Anti-A antibodies

Anti-B antibodies

Both Anti-A and Anti-B

No antibodies

Explanation: Individuals with Type A blood produce antibodies against the B antigen they lack.

Question 35 of 40

Why is Type AB+ blood classified as the universal recipient?

It lacks all clotting factors

It has no antigens on its red blood cells

Its plasma contains no anti-A, anti-B, or anti-Rh antibodies

It contains high levels of albumin

Explanation: Lacking these antibodies means the recipient's blood will not attack incoming donor red blood cells.

Question 36 of 40

What is the clear fluid called once it leaves tissue spaces and enters lymphatic capillaries?

Plasma

Serum

Lymph

Intracellular matrix

Explanation: Interstitial fluid is renamed lymph the moment it diffuses past the cells of lymphatic capillaries.

Question 37 of 40

Which lymphatic organs are specialized to filter blood, destroy old RBCs, and act as a blood reservoir?

Lymph nodes

Spleen

Thymus

Lacteals

Explanation: The spleen acts as a blood filter, removing worn-out red blood cells and recycling iron.

Question 38 of 40

What are the specialized lymph capillaries located in the intestinal villi that absorb dietary fats called?

Aquaporins

Arterioles

Venules

Lacteals

Explanation: Lacteals absorb fats and fat-soluble vitamins, giving lymph in this area a milky appearance.

Question 39 of 40

Where do T-lymphocytes migrate to undergo maturation and select for immune competence?

Thyroid gland

Thymus gland

Spleen

Bone marrow

Explanation: T-lymphocytes migrate from bone marrow to the thymus gland to mature into functional immune cells.

Question 40 of 40

Into which blood vessels does the lymphatic system empty its fluid to return it to central circulation?

Hepatic portal vein

Subclavian veins

Renal arteries

Inferior vena cava

Explanation: Lymphatic ducts drain into the left and right subclavian veins, returning fluid back to the cardiovascular system.

Online Test — Respiration and Transport