Grade 7 : Science (Curiosity) - 9. Animal Life Processes (Set 5) | Concept of Maths

Question 1

The surface area to volume ratio ($SA:V$) is critical for diffusion. If a spherical organism's radius $r$ doubles from 1 unit to 2 units, by what factor does the $SA:V$ ratio change?

Accepted Answer

C) It is halved

Answer

A) It doubles

Answer

B) It stays the same

Answer

D) It quadruples

Question 2

Kleiber's Law states that an animal's metabolic rate $R$ scales with its mass $M$ as $R \propto M^{0.75}$. If an animal is 16 times heavier than another, how much more oxygen will it consume per unit time approximately?

Accepted Answer

B) 8 times

Answer

A) 16 times

Answer

C) 4 times

Answer

D) 32 times

Question 3

In a closed circulatory system, the velocity of blood flow $v$ is inversely proportional to the total cross-sectional area $A$ of the vessels ($v = \frac{Q}{A}$, where $Q$ is constant flow). If the total area of capillaries is 500 times that of the aorta, what is the ratio of velocity in the aorta ($v_a$) to the capillaries ($v_c$)?

Accepted Answer

D) $500 : 1$

Answer

A) $1 : 500$

Answer

B) $1 : 1$

Answer

C) $250 : 1$

Question 4

A ruminant animal like a cow has a stomach divided into four compartments. If the total volume is $V$, and the Rumen occupies 80%, the Reticulum 5%, the Omasum 7%, and the Abomasum the rest, what is the volume of the Abomasum?

Accepted Answer

A) $0.08V$

Answer

B) $0.18V$

Answer

C) $0.12V$

Answer

D) $0.05V$

Question 5

In fish, counter-current exchange in gills maintains a concentration gradient. If water oxygen saturation drops from 100% to 20% and blood saturation rises from 5% to 90%, what is the minimum gradient maintained at any point if the flow is perfectly counter-current?

Accepted Answer

C) 10%

Answer

A) 5%

Answer

B) 80%

Answer

D) 15%

Question 6

An insect's tracheal system relies on diffusion. The time $t$ for a molecule to diffuse a distance $L$ is $t \propto L^2$. If an insect grows 3 times larger in all linear dimensions, by what factor does the time for oxygen to reach its inner tissues increase?

Accepted Answer

B) 9

Answer

A) 3

Answer

C) 27

Answer

D) 6

Question 7

Mammalian lungs have alveoli to increase surface area. If a human lung has 300 million alveoli, each with a radius of 0.1 mm, approximate the total surface area $A$ in $m^2$. (Use $A = N \cdot 4\pi r^2$, $\pi \approx 3$)

Accepted Answer

A) $36 m^2$

Answer

B) $3.6 m^2$

Answer

C) $120 m^2$

Answer

D) $360 m^2$

Question 8

A hummingbird's heart beats 1200 times per minute. If its lifespan is 5 years, how many total heartbeats does it have? (Assume $1 years \approx 5 \cdot 10^5 minutes$)

Accepted Answer

D) $3 \cdot 10^9$

Answer

A) $3 \cdot 10^6$

Answer

B) $6 \cdot 10^7$

Answer

C) $3 \cdot 10^8$

Question 9

Excretion of nitrogenous waste: Ammonia requires 500 ml water per gram of N, Urea requires 50 ml, and Uric acid 10 ml. If a bird excretes 2 g of Nitrogen as Uric acid, how much water does it save compared to a fish excreting the same as Ammonia?

Accepted Answer

C) 980 ml

Answer

A) 490 ml

Answer

B) 900 ml

Answer

D) 1000 ml

Question 10

In the small intestine, villi increase the absorption area. If a flat surface of $1 cm^2$ is covered with 40 villi, each being a cylinder of height 1 mm and radius 0.1 mm, by what factor is the area increased? (Use $\pi \approx 3.14$, Cylinder Area $= 2\pi rh$ neglecting the top)

Accepted Answer

B) 1.25

Answer

A) 0.25

Answer

C) 2.5

Answer

D) 4.0

Question 11

A nerve impulse travels at 100 m/s in a myelinated fiber. In a giant squid axon (unmyelinated), it travels at 20 m/s. If a signal must travel 2 meters from a whale's tail to its brain, how much faster (in seconds) is the myelinated signal?

Accepted Answer

D) 0.08 s

Answer

A) 0.10 s

Answer

B) 0.02 s

Answer

C) 0.05 s

Question 12

Partial pressure of $O_2$ ($P_{O_2}$) in inhaled air is 160 mmHg. In the alveoli, it is 100 mmHg due to mixing with residual air. If the $P_{O_2}$ in deoxygenated blood is 40 mmHg, what is the pressure gradient driving $O_2$ into the blood?

Accepted Answer

A) 60 mmHg

Answer

B) 120 mmHg

Answer

C) 140 mmHg

Answer

D) 20 mmHg

Question 13

An earthworm breathes through its skin. If its skin must stay moist to dissolve $O_2$, and it loses 0.5 mg of water per $1 cm^2$ per hour, how much water does a worm with $20 cm^2$ surface area lose in a day?

Accepted Answer

B) 240 mg

Answer

A) 120 mg

Answer

C) 10 mg

Answer

D) 480 mg

Question 14

The 'Heat Increment of Feeding' means metabolic rate increases after eating. If a python's resting $O_2$ consumption is 10 ml/hr and it increases by 400% after swallowing a large meal, what is its new consumption rate?

Accepted Answer

C) 50 ml/hr

Answer

A) 40 ml/hr

Answer

B) 14 ml/hr

Answer

D) 400 ml/hr

Question 15

A contractile vacuole in a Paramecium pumps out water. If the vacuole has a volume of 10 pL and fires every 5 seconds, what is the rate of water expulsion in $ ext{pL/min}$?

Accepted Answer

B) 120 pL/min

Answer

A) 60 pL/min

Answer

C) 50 pL/min

Answer

D) 300 pL/min

Question 16

In aerobic respiration, 1 molecule of glucose yields approximately 36 ATP. In anaerobic, it yields 2 ATP. To get the same energy as 10 glucose molecules burned aerobically, how many must be burned anaerobically?

Accepted Answer

D) 180

Answer

A) 18

Answer

B) 36

Answer

C) 72

Question 17

If a dog's tidal volume (air per breath) is 0.5 Liters and its respiratory rate is 20 breaths per minute, but 0.15 Liters of each breath stays in the 'dead space' (trachea), what is the actual volume of fresh air reaching the alveoli per minute?

Accepted Answer

A) 7.0 Liters

Answer

B) 10.0 Liters

Answer

C) 3.0 Liters

Answer

D) 8.5 Liters

Question 18

The heart of a blue whale pumps 200 Liters of blood per beat. If its heart rate is 10 beats per minute, how many kiloliters ($1 ext{ kL} = 1000 ext{ L}$) of blood does it pump in one hour?

Accepted Answer

C) 120 kL

Answer

A) 12 kL

Answer

B) 20 kL

Answer

D) 1.2 kL

Question 19

In a closed circuit, if the resistance $R$ of a blood vessel is given by $R \propto \frac{1}{r^4}$ (Poiseuille's Law), and a vessel's radius $r$ is halved due to constriction, what happens to the resistance?

Accepted Answer

B) $R$ increases by 16 times

Answer

A) $R$ increases by 4 times

Answer

C) $R$ increases by 8 times

Answer

D) $R$ decreases by 16 times

Question 20

Pepsin works best at $pH = 2$. If the concentration of $H^+$ ions at $pH = 2$ is $10^{-2} ext{ mol/L}$ and at $pH = 4$ is $10^{-4} ext{ mol/L}$, how many times more acidic is the environment at $pH = 2$ than $pH = 4$?

Accepted Answer

D) 100 times

Answer

A) 2 times

Answer

B) 10 times

Answer

C) 20 times