Grade 7 : Science (Curiosity) - 9. Animal Life Processes (Set 4) | Concept of Maths

Question 1

In a closed circulatory system, if the heart rate (HR) of a mammal is 75 beats per minute and the stroke volume (SV) is 70 mL/beat, calculate the total Cardiac Output (CO) in liters per minute.

Accepted Answer

C) 5.25 L/min

Answer

A) 4.25 L/min

Answer

B) 5.00 L/min

Answer

D) 6.15 L/min

Question 2

During aerobic respiration, if a cell consumes 12 molecules of glucose ($C_6H_{12}O_6$), how many total molecules of $CO_2$ are produced as a byproduct?

Accepted Answer

B) 72

Answer

A) 36

Answer

C) 12

Answer

D) 144

Question 3

An enzyme in the human stomach works optimally at $pH \approx 2.0$. If the concentration of hydrogen ions $[H^+]$ increases by a factor of 10, what is the new pH level?

Accepted Answer

A) 1.0

Answer

B) 3.0

Answer

C) 2.1

Answer

D) 12.0

Question 4

In the human excretory system, the glomerular filtration rate (GFR) is 125 mL/min. If 99% of this filtrate is reabsorbed by the renal tubules, what is the volume of urine produced in 1 hour?

Accepted Answer

D) 75 mL

Answer

A) 1.25 mL

Answer

B) 125 mL

Answer

C) 60 mL

Question 5

A fish moves its operculum to maintain a flow of water over its gills. If the oxygen concentration in water is 10 mg/L and the fish extracts 80% of it, how much oxygen does it obtain from 5 liters of water?

Accepted Answer

B) 40 mg

Answer

A) 8 mg

Answer

C) 50 mg

Answer

D) 4 mg

Question 6

Consider a spherical model of an alveolus with a radius $r = 0.1 ext{ mm}$. If the radius doubles to 0.2 mm, by what factor does the surface area available for gas exchange increase?

Accepted Answer

C) 4

Answer

A) 2

Answer

B) 3

Answer

D) 8

Question 7

In the human small intestine, the presence of villi increases the surface area significantly. If a flat tube has a surface area of $S$, and villi increase this by a factor of 30, and microvilli further increase that result by a factor of 20, what is the total surface area relative to $S$?

Accepted Answer

A) $600S$

Answer

B) $50S$

Answer

C) $3020S$

Answer

D) $100S$

Question 8

A person at rest has a breathing rate of 15 breaths/min and a tidal volume (air per breath) of 500 mL. During exercise, the rate increases to 40 breaths/min and tidal volume to 2000 mL. What is the ratio of exercise ventilation to resting ventilation?

Accepted Answer

B) $32:3$

Answer

A) $4:1$

Answer

C) $10:1$

Answer

D) $8:1$

Question 9

If the partial pressure of $O_2$ ($P_{O2}$) in the alveoli is 104 mmHg and in the deoxygenated blood arriving at the lungs it is 40 mmHg, what is the pressure gradient driving diffusion?

Accepted Answer

D) 64 mmHg

Answer

A) 144 mmHg

Answer

B) 1.6 mmHg

Answer

C) 40 mmHg

Question 10

Bile salts emulsify fats, breaking large droplets into smaller ones. If one large spherical fat droplet with diameter $D$ is broken into 8 smaller identical spherical droplets, what is the new diameter $d$ of each smaller droplet?

Accepted Answer

C) $D/2$

Answer

A) $D/8$

Answer

B) $D/4$

Answer

D) $D/\sqrt{8}$

Question 11

In a grasshopper (tracheal system), air enters through spiracles. If a spiracle is roughly circular with radius $r$, and the insect's oxygen demand triples, by what factor must $r$ increase to maintain flow (assuming flow rate is proportional to area)?

Accepted Answer

A) $\sqrt{3}$

Answer

B) 3

Answer

C) 9

Answer

D) 1.5

Question 12

Blood pressure is measured as Systolic/Diastolic. If a patient has a reading of $130/90$, calculate their Pulse Pressure (PP) and Mean Arterial Pressure (MAP). ($MAP \approx ext{Diastolic} + \frac{1}{3}PP$)

Accepted Answer

B) $PP=40, MAP=103.3$

Answer

A) $PP=40, MAP=110$

Answer

C) $PP=220, MAP=110$

Answer

D) $PP=40, MAP=115$

Question 13

Anaerobic respiration in yeast produces 2 ATP per glucose, while aerobic respiration produces 36 ATP. How much more glucose must yeast consume anaerobically to produce the same amount of energy as 5 molecules of glucose consumed aerobically?

Accepted Answer

C) 85 molecules MORE

Answer

A) 18 times more

Answer

B) 90 molecules

Answer

D) 180 molecules

Question 14

The velocity of blood flow ($v$) is inversely proportional to the total cross-sectional area ($A$) of the vessels ($v = Q/A$). If the total area of capillaries is 1000 times that of the aorta, how does the velocity in capillaries compare to the aorta?

Accepted Answer

D) $1000 	imes$ slower

Answer

A) $1000 	imes$ faster

Answer

B) Same speed

Answer

C) $100 	imes$ slower

Question 15

Nitrogenous waste: Ammonia is highly toxic and requires 500 mL of water to excrete 1 g. Urea requires 50 mL. If an aquatic animal produces 4 g of nitrogen waste as ammonia, how much water does it need compared to a land animal producing the same as urea?

Accepted Answer

A) 1800 mL more

Answer

B) $10 	imes$ less

Answer

C) 2000 mL total

Answer

D) 200 mL total

Question 16

If the pH of the small intestine is 8.0 and the pH of the stomach is 2.0, what is the difference in the concentration of $H^+$ ions between the two organs?

Accepted Answer

C) $1,000,000 	imes$

Answer

A) $6 	imes$

Answer

B) $60 	imes$

Answer

D) $10,000 	imes$

Question 17

A heartbeat cycle lasts 0.8 seconds. If atrial systole lasts 0.1 s and ventricular systole lasts 0.3 s, what is the duration of the complete cardiac diastole (joint diastole)?

Accepted Answer

B) 0.4 s

Answer

A) 0.5 s

Answer

C) 0.8 s

Answer

D) 0.2 s

Question 18

If a human lung has 300 million alveoli and each has a surface area of $0.25 ext{ mm}^2$, what is the approximate total surface area of the lungs in square meters ($1 m^2 = 1,000,000 ext{ mm}^2$)?

Accepted Answer

D) $75 m^2$

Answer

A) $7.5 m^2$

Answer

B) $750 m^2$

Answer

C) $0.75 m^2$

Question 19

In the double circulation of a bird, blood travels: Heart $\rightarrow$ Lungs $\rightarrow$ Heart $\rightarrow$ Body $\rightarrow$ Heart. If the oxygen saturation is 70% leaving the body and 98% leaving the lungs, what is the saturation in the Right Ventricle?

Accepted Answer

B) 70%

Answer

A) 98%

Answer

C) 84%

Answer

D) 0%

Question 20

A nerve impulse travels at 100 m/s. If a stimulus is applied to a toe 1.5 m away from the spinal cord, and the reflex arc involves a total path of 3.0 m (to cord and back), how long does the impulse take to travel the distance (excluding synaptic delay)?

Accepted Answer

A) 0.03 s

Answer

B) 0.3 s

Answer

C) 0.015 s

Answer

D) 30 ms