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Life Processes - Q&A

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

Answer: (c) excretion.
Explanation: The kidneys filter waste products from the blood, such as urea and excess salts, and excrete them in the form of urine. This makes them the primary organs of the excretory system.

[Image of human excretory system]

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

Answer: (a) transport of water.
Explanation: Xylem tissue is responsible for conducting water and dissolved minerals from the roots to the stems and leaves. Phloem is responsible for transporting food.

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

Answer: (d) all of the above.
Explanation: Autotrophic nutrition (photosynthesis) is the process by which green plants make their own food. The equation for photosynthesis is:
6CO₂ + 12H₂O + Sunlight/Chlorophyll → C₆H₁₂O₆ + 6O₂ + 6H₂O
This shows that Carbon dioxide, Water, Chlorophyll, and Sunlight are all essential.

[Image of photosynthesis diagram]

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

Answer: (b) mitochondria.
Explanation: The first step of respiration (Glycolysis) happens in the cytoplasm and breaks glucose into pyruvate. The second step, where pyruvate is completely broken down into CO₂, water, and energy (ATP), happens in the mitochondria. This is known as aerobic respiration.

[Image of mitochondria structure]

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

Answer:
Where: The digestion of fats primarily takes place in the small intestine.
How:
1. Emulsification by Bile: Fats are present as large globules which are difficult for enzymes to act on. Bile salts (from the liver) break them down into smaller globules. This is called emulsification.
2. Digestion by Lipase: The pancreas secretes an enzyme called lipase. Lipase acts on the emulsified fats and breaks them down into fatty acids and glycerol.

[Image of fat digestion process]

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

Answer:
Saliva contains an enzyme called salivary amylase. Its roles are:
1. Chemical Digestion: It breaks down complex starch (carbohydrates) into simpler sugars (maltose).
2. Lubrication: It moistens the food, making it easier to swallow (forming a bolus).

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

Answer:
Necessary Conditions:
1. Carbon dioxide (CO₂): Taken from the air through stomata.
2. Water (H₂O): Absorbed by roots from the soil.
3. Sunlight: Provides energy for the reaction.
4. Chlorophyll: The green pigment in leaves that traps sunlight.

By-products:
1. Oxygen (O₂): Released into the atmosphere.
2. Water (H₂O): Released as vapour (transpiration).

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

Answer:

Feature	Aerobic Respiration	Anaerobic Respiration
Oxygen Requirement	Takes place in the presence of oxygen.	Takes place in the absence of oxygen.
End Products	Carbon dioxide (CO₂) and Water.	Ethanol & CO₂ (in yeast) OR Lactic Acid (in muscles).
Energy Released	Large amount of energy is released.	Small amount of energy is released.
Site	Cytoplasm and Mitochondria.	Only in Cytoplasm.

Organisms using Anaerobic Respiration: Yeast (fungi) and some bacteria.

9. How are the alveoli designed to maximise the exchange of gases?

Answer: Alveoli are tiny balloon-like structures in the lungs that maximise gas exchange by:
1. Large Surface Area: There are millions of alveoli, providing a massive surface area for gases to diffuse.
2. Thin Walls: The walls of alveoli are very thin (one cell thick), allowing easy diffusion of gases.
3. Rich Blood Supply: They are surrounded by a dense network of blood capillaries to efficiently transport oxygen and carbon dioxide.

[Image of alveoli structure]

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

Answer: Haemoglobin is the red pigment in blood that carries oxygen from the lungs to all body cells.
Consequences of deficiency (Anemia):
1. Reduced Oxygen Supply: The blood will not be able to carry enough oxygen to the tissues.
2. Fatigue: Less oxygen means less energy production, leading to tiredness and weakness.
3. Breathlessness: The body may try to compensate by breathing faster.

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

Answer:
Description: In humans, blood flows through the heart twice during one complete cycle.
1. Pulmonary Circulation: Deoxygenated blood moves from the heart to the lungs (to get oxygen) and returns as oxygenated blood to the heart.
2. Systemic Circulation: Oxygenated blood moves from the heart to the rest of the body and returns as deoxygenated blood to the heart.

Why is it necessary?
It separates oxygenated and deoxygenated blood. This ensures a highly efficient supply of oxygen to the body, which is essential for warm-blooded animals like humans who need high energy to maintain their body temperature.

[Image of double circulation in humans]

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

Answer:

Feature	Xylem	Phloem
Material Transported	Water and minerals.	Food (sugars/amino acids).
Direction	Unidirectional (Upwards from roots).	Bidirectional (Up and down).
Mechanism	Physical forces (Transpiration pull).	Active transport (Uses energy/ATP).
Cells	Mostly dead cells (Vessels/Tracheids).	Living cells (Sieve tubes/Companion cells).

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

Answer:

Feature	Alveoli (Lungs)	Nephrons (Kidneys)
Structure	Balloon-like sacs with thin walls.	Tubular structure with a cup-shaped end (Bowman's capsule).
Function	Exchange of gases (O₂ and CO₂).	Filtration of blood and formation of urine.
Location	Found in the Lungs.	Found in the Kidneys.
Blood Supply	Surrounded by capillaries to take O₂ and release CO₂.	Surrounded by capillaries to filter waste and reabsorb useful substances.

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Quick Review Flashcards - Click to flip and test your knowledge!

Question

Why is visible movement alone insufficient as a defining characteristic of life?

Answer

Some living things, such as plants, may not show visible growth, and some animals can breathe without perceptible movement.

Question

Which type of invisible movement is considered essential for life by professional biologists?

Answer

Molecular movement.

Question

Why must living organisms continuously move molecules around for repair and maintenance?

Answer

The organised, ordered nature of living structures is likely to break down over time due to environmental effects.

Question

Definition: Life Processes

Answer

The group of processes that together perform the maintenance job required to keep an organism alive.

Question

What is the primary source of energy transferred from outside an organism to the inside for maintenance?

Answer

Food.

Question

The process of transferring a source of energy from outside the body to the inside is commonly called _____.

Answer

Nutrition.

Question

Why are most food sources on Earth carbon-based?

Answer

Life on Earth depends on carbon-based molecules.

Question

Which type of chemical reactions are the most common means used by organisms to break down molecules for energy?

Answer

Oxidising-reducing reactions.

Question

Definition: Respiration

Answer

The process of acquiring oxygen from outside the body and using it to break down food sources for cellular needs.

Question

Why is simple diffusion insufficient for the oxygen requirements of complex multi-cellular organisms?

Answer

All cells may not be in direct contact with the surrounding environment.

Question

In multi-cellular organisms, what system is needed to carry food and oxygen to cells that are not in direct contact with the environment?

Answer

A transportation system.

Question

The biological process involved in removing harmful metabolic waste by-products from the body is called _____.

Answer

Excretion.

Question

Term: Autotrophs

Answer

Organisms that use simple food material obtained from inorganic sources like $CO_{2}$ and water, such as green plants.

Question

How do heterotrophs obtain the simple substances needed for the growth of their bodies?

Answer

They utilise complex substances that are broken down into simpler ones using enzymes.

Question

What term is used for the biological catalysts that organisms use to break down complex food substances?

Answer

Enzymes.

Question

Through which process do autotrophs convert external substances like carbon dioxide and water into stored energy?

Answer

Photosynthesis.

Question

In what form do plants store carbohydrates that are not used immediately for energy?

Answer

Starch.

Question

In humans, energy derived from food that is not used immediately is stored in the body in the form of _____.

Answer

Glycogen.

Question

What is the first event that occurs during the process of photosynthesis?

Answer

Absorption of light energy by chlorophyll.

Question

During photosynthesis, light energy is converted to chemical energy to split water molecules into which two elements?

Answer

Hydrogen and oxygen.

Question

What happens to carbon dioxide during the final stages of photosynthesis?

Answer

It is reduced to carbohydrates.

Question

How does the timing of carbon dioxide uptake in desert plants differ from most other plants?

Answer

They take up carbon dioxide at night and prepare an intermediate that is acted upon by energy during the day.

Question

Which specific cell organelles contain the pigment chlorophyll?

Answer

Chloroplasts.

Question

What are the tiny pores present on the surface of leaves called?

Answer

Stomata.

Question

Which cells are responsible for the opening and closing of stomatal pores?

Answer

Guard cells.

Question

Under what condition do guard cells cause the stomatal pore to open?

Answer

When water flows into the guard cells, causing them to swell.

Question

Why do plants close their stomata when they do not need carbon dioxide for photosynthesis?

Answer

To prevent the loss of large amounts of water.

Question

Which chemical substance is used in photosynthesis experiments to absorb carbon dioxide?

Answer

Potassium hydroxide ($KOH$).

Question

Which essential element is used by plants specifically for the synthesis of proteins?

Answer

Nitrogen.

Question

In what inorganic form do terrestrial plants usually take up nitrogen from the soil?

Answer

Nitrates or nitrites.

Question

Give an example of a fungus that breaks down food material outside the body before absorption.

Answer

Bread moulds (or yeast/mushrooms).

Question

What is the parasitic nutritive strategy?

Answer

Deriving nutrition from plants or animals without killing them.

Question

How does an Amoeba ingest food particles?

Answer

By using temporary finger-like extensions of the cell surface (pseudopodia) to form a food-vacuole.

Question

How does Paramoecium move food to its specific ingestion spot?

Answer

By the movement of cilia which cover the entire surface of the cell.

Question

Which enzyme found in human saliva breaks down complex starch into simple sugar?

Answer

Salivary amylase.

Question

What are the rhythmic contraction movements of the alimentary canal muscles that push food forward called?

Answer

Peristaltic movements.

Question

Which three substances are secreted by the gastric glands in the stomach wall?

Answer

Hydrochloric acid, pepsin, and mucus.

Question

What is the function of hydrochloric acid in the human stomach?

Answer

It creates an acidic medium to facilitate the action of the protein-digesting enzyme pepsin.

Question

What is the primary role of mucus in the stomach?

Answer

It protects the inner lining of the stomach from the action of hydrochloric acid.

Question

The exit of food from the stomach is regulated by which muscle?

Answer

The sphincter muscle.

Question

Why do herbivores like cows require a longer small intestine than carnivores like tigers?

Answer

To allow the cellulose in their diet to be fully digested.

Question

Which organ is the site of the complete digestion of carbohydrates, proteins, and fats?

Answer

The small intestine.

Question

What is the function of bile salts in the small intestine?

Answer

They break down large fat globules into smaller ones (emulsification) to increase enzyme efficiency.

Question

Which pancreatic enzyme is responsible for the digestion of proteins in the small intestine?

Answer

Trypsin.

Question

Which pancreatic enzyme is responsible for breaking down emulsified fats?

Answer

Lipase.

Question

During digestion in the small intestine, proteins are finally converted into _____.

Answer

Amino acids.

Question

What are the final products of carbohydrate and fat digestion in the small intestine?

Answer

Glucose (from carbohydrates) and fatty acids and glycerol (from fats).

Question

What are villi and what is their function?

Answer

Finger-like projections in the small intestine that increase the surface area for the absorption of food.

Question

What is the primary function of the large intestine in the human digestive system?

Answer

To absorb water from unabsorbed food material before it is removed from the body.

Question

In the first step of respiration, glucose is broken down in the cytoplasm into which molecule?

Answer

Pyruvate.

Question

Where in the cell does the aerobic breakdown of pyruvate into carbon dioxide and water occur?

Answer

The mitochondria.

Question

What are the products of anaerobic respiration (fermentation) in yeast?

Answer

Ethanol, carbon dioxide, and energy.

Question

What causes muscle cramps during sudden, intense physical activity?

Answer

The build-up of lactic acid in muscle cells due to anaerobic breakdown of pyruvate.

Question

What is the energy currency for most cellular processes?

Answer

ATP (Adenosine triphosphate).

Question

Approximately how much energy is released when the terminal phosphate linkage in ATP is broken using water?

Answer

$30.5\text{ kJ/mol}$.

Question

During the night, which gas exchange activity is the major event occurring in plants?

Answer

Carbon dioxide elimination.

Question

Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?

Answer

The amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air.

Question

What is the purpose of the rings of cartilage present in the human throat?

Answer

To ensure that the air-passage does not collapse.

Question

In which balloon-like structures in the lungs does the exchange of gases take place?

Answer

Alveoli.

Question

Which respiratory pigment in human beings has a very high affinity for oxygen?

Answer

Haemoglobin.