Question 1

Q1: The kidneys in human beings are a part of the system for (a) nutrition. (b) respiration. (c) excretion. (d) transportation.

Accepted Answer

(c) excretion. The kidneys are the primary organs of the excretory system, responsible for filtering waste products from the blood to produce urine.

Question 2

Q10: What would be the consequences of a deficiency of haemoglobin in our bodies?

Accepted Answer

Haemoglobin is the respiratory pigment in our red blood cells responsible for transporting oxygen from the lungs to all the body tissues. A deficiency of haemoglobin would lead to a condition called anemia. The consequences would be: 1.  Reduced Oxygen Supply: The oxygen-carrying capacity of the blo...

Question 3

Q11: Describe double circulation of blood in human beings. Why is it necessary?

Accepted Answer

Double Circulation: Double circulation is a system in which the blood passes through the heart twice during one complete cycle of circulation through the body. The human heart is divided into four chambers, and the pathway consists of two distinct circuits: 1.  Pulmonary Circulation: This circuit mo...

Question 4

Q12: What are the differences between the transport of materials in xylem and phloem?

Accepted Answer

Question 5

Q13: Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Accepted Answer

Question 6

Q2: The xylem in plants are responsible for (a) transport of water. (b) transport of food. (c) transport of amino acids. (d) transport of oxygen.

Accepted Answer

(a) transport of water. The xylem is the vascular tissue in plants that conducts water and dissolved minerals from the roots to the rest of the plant.

Question 7

Q3: The autotrophic mode of nutrition requires (a) carbon dioxide and water. (b) chlorophyll. (c) sunlight. (d) all of the above.

Accepted Answer

(d) all of the above. Autotrophic nutrition, specifically photosynthesis, requires carbon dioxide, water, chlorophyll to trap sunlight, and sunlight as the energy source.

Question 8

Q4: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in (a) cytoplasm. (b) mitochondria. (c) chloroplast. (d) nucleus.

Accepted Answer

(b) mitochondria. This process is aerobic respiration. The initial breakdown of glucose to pyruvate occurs in the cytoplasm, but the complete breakdown of pyruvate into carbon dioxide, water, and energy occurs in the mitochondria.

Question 9

Q5: How are fats digested in our bodies? Where does this process take place?

Accepted Answer

The digestion of fats primarily takes place in the small intestine. The process involves two main steps: 1.  Emulsification: Fats arrive in the small intestine in the form of large globules. Bile juice, secreted by the liver, contains bile salts that break down these large fat globules into much sma...

Question 10

Q6: What is the role of saliva in the digestion of food?

Accepted Answer

Saliva plays two important roles in the digestion of food: 1.  Moistening Food: Saliva wets the food, making it softer and easier to chew and form into a bolus that can be swallowed smoothly. 2.  Chemical Digestion: Saliva contains an enzyme called salivary amylase. This enzyme begins the chemical d...

Question 11

Q7: What are the necessary conditions for autotrophic nutrition and what are its byproducts?

Accepted Answer

The necessary conditions for autotrophic nutrition (specifically photosynthesis) are: 1.  Carbon Dioxide ($CO_2$): Obtained from the atmosphere. 2.  Water ($H_2O$): Absorbed from the soil. 3.  Sunlight: As a source of energy. 4.  Chlorophyll: The green pigment that traps sunlight energy. The byprodu...

Question 12

Q8: What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Accepted Answer

Question 13

Q9: How are the alveoli designed to maximise the exchange of gases?

Accepted Answer

The alveoli are designed to maximise the exchange of gases in several ways: 1.  Large Surface Area: There are millions of alveoli in the lungs, which collectively provide an enormous surface area (about 80 $m^2$) for gas exchange to occur. 2.  Thin Walls: The wall of each alveolus is extremely thin,...

Question 14

Q1: Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Accepted Answer

In large multicellular organisms like humans, all the cells are not in direct contact with the surrounding environment. Simple diffusion is a very slow process and would take an extremely long time for oxygen to reach all the cells of the body. For instance, the text mentions it would take about 3 y...

Question 15

Q2: What criteria do we use to decide whether something is alive?

Accepted Answer

The criteria used to decide whether something is alive include: 1.  Visible Movements: Obvious movements like running, breathing, or growth are common indicators of life. 2.  Molecular Movements: The most fundamental criterion is the presence of molecular movements. Living structures are highly orga...

Question 16

Q3: What are outside raw materials used for by an organism?

Accepted Answer

An organism uses outside raw materials for two main purposes: 1.  Source of Energy: Raw materials, which we call food, are broken down through processes like respiration to provide energy. This energy is essential for carrying out various life processes and maintaining the organised structure of the...

Question 17

Q4: What processes would you consider essential for maintaining life?

Accepted Answer

The processes essential for maintaining life, collectively known as life processes, are: 1.  Nutrition: The process of taking in food (a source of energy and raw materials) from outside the body. 2.  Respiration: The process of breaking down food sources to release energy for cellular needs. 3.  Tra...

Question 18

Q1: What are the differences between autotrophic nutrition and heterotrophic nutrition?

Accepted Answer

Question 19

Q2: Where do plants get each of the raw materials required for photosynthesis?

Accepted Answer

Plants obtain the raw materials for photosynthesis from the following sources: 1.  Carbon Dioxide ($CO_2$): Taken from the atmosphere through tiny pores on the surface of the leaves called stomata. 2.  Water ($H_2O$): Absorbed from the soil by the roots. 3.  Sunlight: Absorbed by chlorophyll, the gr...

Question 20

Q3: What is the role of the acid in our stomach?

Accepted Answer

The acid in our stomach, which is hydrochloric acid (HCl), has two main roles: 1.  Activates Pepsin: It creates an acidic medium in the stomach, which is necessary for the protein-digesting enzyme pepsin to function effectively. 2.  Kills Germs: It kills any harmful bacteria or other microorganisms...

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