Lesson: Life Processes

# Question 1

Kidneys in human beings are a part of a system meant for ____________.

(a) nutrition

(b) respiration

(c) excretion

(d) transportation

(c)

# Question 2

The xylem in plants is responsible for

(a) transport of water

(b) transport of food

(c) transport of amino acids

(d) transport of oxygen

(a)

# Question 3

The autotrophic mode of nutrition requires

(a) carbon dioxide and water.

(b) chlorophyll.

(c) sunlight.

(d) all of the above.

(d)

# Question 4

The breakdown of pyruvate to give carbon dioxide, water and energy takes place in:

(a) cytoplasm.

(b) mitochondria.

(c) chloroplast.

(d) nucleus.

(b)

# Question 5

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

## Solution:

Fats are present in the small intestine in the form of large globules. The small intestine receives the bile salts from the liver. The bile salt breaks down the large fat globules into smaller globules so that the pancreatic enzyme lipase can easily act on them.

# Question 6

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

## Solution:

Saliva contains a digestive enzyme called salivary amylase, which breaks down the complex molecules (starch) into sugar.

# Question 7

What are the necessary conditions for autotrophic nutrition and what are its by-products?

## Solution:

Conditions for autotrophic nutrition: Presence of carbon dioxide, water, chlorophyll, and sunlight. By-products of autotrophic nutrition: Carbohydrates and Oxygen

# Question 8

## Solution:

 Aerobic respiration Anaerobic respiration It occurs in the presence of ${O}_{2}$. It occurs in the absence of ${O}_{2}$. It involves exchange of gases between an organism and outside environment. Exchange of gases is absent. It occurs in cytoplasm and mitochondria. It occurs only in cytoplasm. It always releases $C{O}_{2}$ and ${H}_{2}O$. End product is either lactic acid or alcohol.

Yeast and bacteria use anaerobic mode of respiration.

# Question 9

How are the alveoli designed to maximize the exchanges of gases?

## Solution:

There are millions of alveoli in our lungs. The presence of alveoli provides large surface for exchange of gases. The walls of alveoli have an extensive network of blood vessels that ensure maximum exchange of gases.

# Question 10

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

## Solution:

Haemoglobin carries oxygen in our blood. Therefore, deficiency of haemoglobin in blood can affect oxygen supplying capacity of the blood. This can lead to deficiency of oxygen in body cells and lead to a disease called anaemia.

# Question 11

Describe double circulation in human beings. Why is it necessary?

## Solution:

Humans are warm blooded. Therefore, they need extra energy to maintain body temperature. To ensure this, it is essential to maintain separation of oxygenated and de-oxygenated blood.  To do that, blood flows in and out of the heart twice.  This is known as double circulation.

# Question 12

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

## Solution:

 Xylem Phloem Xylem helps in the transport of water and minerals. Phloem helps in the transport of food. Water is transported upwards from roots to all other plant parts. Food is transported in both upward and downward directions. Transport in xylem occurs with the help of simple physical forces such as transpiration pull. Transport of food in phloem requires energy in the form of ATP.

# Question 13

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

## Solution:

 Alveoli Nephrons Alveoli are sac like structures. Nephrons are tubular structures present inside kidneys. The walls of alveoli are one cell thick and they contain an extensive network of blood capillaries. Nephrons are made of glomerulus, bowman’s capsule, and a long renal tube. Alveoli are the site of gaseous exchange. Nephrons are a basic filtration unit. The exchange of ${O}_{2}$ and $C{O}_{2}$ takes place between the blood capillaries that surround the alveoli and the gases present in the alveoli. Blood enters the kidneys through the renal artery. The blood gets filtered in nephrons. The nitrogenous waste in the form of urine is collected by the collecting duct.