Life Process

 

1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans? -

ANSWER=
As in multicellular organisms, all the cells are not in direct contact with environment, simple diffusion does not meet the requirement of all the body cells to get sufficient oxygen.
the following reasons:
1. Large Body Size and Complexity
2. Greater Oxygen Demand
3. Larger Distance Between Cells and Environment
4. Need for Rapid Transport System
Conclusion:
Thus, simple diffusion is adequate only for small and simple organisms. For complex, multicellular organisms like humans, specialized organ systems are necessary to fulfill the high oxygen demands efficiently

 

2. What Criteria Do We Use to Decide Whether Something is Alive? -

ANSWER= To determine whether something is alive, scientists and biologists look for certain characteristic features that all living organisms share. These include:
1. Movement
2. Respiration
3. Sensitivity to Stimuli
4. Growth
5. Reproduction
6. Excretion
7. Nutrition
8. Cellular Organization
9. Metabolism
✅ Conclusion: If an object shows all or most of the above features, it is considered alive. For example, a car moves but does not grow, reproduce, or respire—so it's not alive. A plant grows, respires, reproduces, and responds—so it's alive.

 

3. What Are Outside Raw Materials Used for by an Organism? -

ANSWER= Outside raw materials are substances taken from the environment that an organism needs to survive, grow, and carry out life processes.
✅ Uses of Outside Raw Materials by an Organism:
1. Energy Production
• Food (glucose, carbohydrates, etc.) provides energy through respiration.
• Plants use sunlight (though not a material, it's essential) and carbon dioxide to make food via photosynthesis.
2. Growth and Repair
• Proteins, minerals, and vitamins from food help in cell formation, tissue repair, and growth.
3. Maintenance of Life Functions
• Water is needed for:
o Transport of nutrients
o Removal of waste (excretion)
o Chemical reactions in the body (metabolism)
• Oxygen is needed for aerobic respiration to release energy from food.
4. Photosynthesis (in plants)
• Plants use:
o Carbon dioxide from air
o Water from soil
o Minerals (like nitrogen, magnesium, phosphorus) for making chlorophyll, proteins, DNA, etc.
✅ Conclusion:
Outside raw materials are essential inputs that organisms use for energy, growth, repair, and survival. Without them, life processes cannot occur.

 

4. What processes would you consider essential for maintaining life? -

ANSWER= To stay alive, all living organisms must carry out certain life processes. These are basic activities that ensure survival, growth, and reproduction.
Process - Function
Nutrition - Provides raw materials & energy
Respiration - Releases energy from food
Transportation - Distributes substances throughout body
Excretion - Removes metabolic waste
Reproduction - Produces offspring
Control & Coordination - Regulates body activities
Metabolism - All life-sustaining chemical reactions
Homeostasis - Keeps internal conditions stable

 

5. What are the differences between autotrophic nutrition and heterotrophic nutrition? -

ANSWER= Differences Between Autotrophic and Heterotrophic Nutrition

Autotrophic Nutrition
1. Definition - Mode of nutrition in which organisms make their own food from raw materials like CO₂ and H₂O using sunlight
2. Food Source - Inorganic substances (CO₂, H₂O, sunlight)
3. Organisms - Mostly green plants, algae, some bacteria
4. Process Used - Photosynthesis (mainly), sometimes chemosynthesis
5. Energy Source - Sunlight (in photosynthesis)
6. Chlorophyll Requirement - Required (for photosynthesis)
7. Examples - Green plants, cyanobacteria, algae

Heterotrophic Nutrition
1. Definition - Mode of nutrition in which organisms depend on other organisms for food
2. Food Source - Organic food from plants or other animals
3. Organisms - All animals, fungi, most bacteria, and non-green plants
4. Process Used - Ingestion, digestion, absorption, assimilation
5. Energy Source - Energy is obtained from the food they consume
6. Chlorophyll - Not required
7. Examples - Humans, lions, mushrooms, amoeba

 

6. Where do plants get each of the raw materials required for photosynthesis? -

ANSWER=
• CO₂ → From air (via stomata)
• H₂O → From soil (via roots)
• Sunlight → From the Sun (absorbed by chlorophyll)
• Chlorophyll → from chloroplast of green plants
These together enable the plant to synthesize glucose (food) and release oxygen as a by-product.

 

7. What is the role of the acid in our stomach? -

ANSWER= Role of Acid in Our Stomach (Hydrochloric Acid - HCl):
The stomach secretes hydrochloric acid (HCl) which plays several important roles in the process of digestion.
Functions of HCl in the Stomach:
1. Activates pepsin enzyme
2. Maintains acidic pH
3. Kills harmful microbes
4. Aids in food breakdown

 

8. What is the function of digestive enzymes? -

ANSWER= Digestive enzymes convert large, insoluble food molecules into small, water-soluble molecules that can be absorbed into the bloodstream and used by the body for energy, growth, and repair.

 

9. How is the Small Intestine Designed to Absorb Digested Food? -

ANSWER= The small intestine is specially adapted to efficiently absorb the digested nutrients into the bloodstream. Here's how:
✅ Key Structural Features for Absorption:
1. Length: It is about 6 meters long, providing a large surface area for absorption.
2. Villi (Finger-like Projections): The inner lining of the small intestine has thousands of tiny projections called villi.
Villi increase the surface area greatly, enhancing absorption.
3. Thin Walls: - The walls of the villi are one-cell thick, allowing easy diffusion of nutrients into blood vessels.
4. Rich Blood Supply: - Each villus contains a network of blood capillaries and a lymph vessel (lacteal) to transport absorbed nutrients.

 

10. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration? -

ANSWER= Terrestrial organisms (like humans, birds, and land animals) breathe air, while aquatic organisms (like fish) obtain oxygen from water.
The key advantage lies in the oxygen content and efficiency of respiration:
1. Higher Oxygen Availability in Air:
o Air contains ~21% oxygen, while water contains much less dissolved oxygen (only about 1-2% by volume).
o This means terrestrial organisms have easier and faster access to oxygen compared to aquatic organisms.
2. Less Energy for Breathing:
o Terrestrial organisms spend less energy to breathe air than aquatic animals do to extract oxygen from water.
3. Efficient Respiratory Systems:
o Lungs (in land animals) are highly efficient for gas exchange due to large surface area and direct contact with oxygen-rich air.
4. No Need to Filter Water:
o Aquatic organisms must filter large volumes of water to get enough oxygen, which is energy-consuming.

Summary - The rate of breathing is slower in terrestrial organisms as compared to aquatic organisms. This is due to the fact that in water, the amount of oxygen is less as compared to air so, in aquatic organisms the rate of breathing is faster.

 

11. What are the different ways in which glucose is oxidised to provide energy in various organisms? -

ANSWER= Different Ways Glucose is Oxidised to Provide Energy in Organisms
Glucose is a key source of energy in all organisms. It is oxidised (broken down) during cellular respiration to release energy. The process varies based on the presence or absence of oxygen.

1. Aerobic Respiration (In the presence of oxygen)
• Organisms: Humans, animals, plants, most fungi.
• Location: Occurs in the mitochondria.
• Equation: Glucose + O2 → CO2 + H2O + Energy (ATP)
• Energy Yield: High (about 38 ATP molecules per glucose).

2. Anaerobic Respiration (In the absence of oxygen)
a) In some organisms like yeast (Alcoholic Fermentation)
• Equation: Glucose → Alcohol (ethanol) + CO2 + Energy
• Energy Yield: Low (only 2 ATP molecules per glucose).
b) In human muscles during heavy exercise
• Equation: Glucose → Lactic Acid + Energy
• Condition: Occurs when oxygen supply is limited (e.g., during sprinting).
• Energy Yield: Low (only 2 ATP molecules), and causes muscle fatigue.

 

12. How is oxygen and carbon dioxide transported in human beings? -

ANSWER=
Transport of Oxygen and Carbon Dioxide in Human Beings
The human circulatory and respiratory systems work together to transport oxygen (O₂) to body tissues and remove carbon dioxide (CO₂) from them. Oxygen is mainly carried by hemoglobin, while carbon dioxide is mainly transported as bicarbonate ions.

1. Transport of Oxygen (O₂)

• Source: Inhaled through lungs → reaches alveoli (air sacs).
• Transport Medium: Blood, specifically red blood cells (RBCs).
• Key Molecule: Hemoglobin (a red pigment in RBCs).
➤ Process:
• Oxygen from alveoli diffuses into blood capillaries.
• Oxygen binds with hemoglobin in RBCs to form oxyhemoglobin. Hb + O2 → HbO2
• This oxyhemoglobin travels via blood to various tissues.
• In tissues, oxygen is released and diffuses into body cells for cellular respiration.

2. Transport of Carbon Dioxide (CO₂)

• Source: Produced as a waste product during respiration in body cells.
• Transport Medium: Blood (mostly in plasma, some in RBCs).
➤ Forms of Transport:
• 70% as bicarbonate ions (HCO₃⁻) dissolved in plasma.
• 20-25% combines with hemoglobin as carbaminohemoglobin.
• 5-10% is dissolved directly in plasma.
➤ Process:
• CO₂ diffuses from body cells into blood capillaries.
• It is mostly converted into bicarbonate ions for easy transport.
• Blood carries CO₂ to lungs, where:
o Bicarbonate is reconverted into CO₂.
o CO₂ diffuses into alveoli and is exhaled.

 

13. How Are the Lungs Designed in Human Beings to Maximise the Area for Exchange of Gases? -

ANSWER=
The lungs are intricately designed with millions of alveoli, a rich blood supply, and thin, moist walls, all working together to provide a vast surface area and efficient gas exchange to support life
The human circulatory and respiratory systems work together to transport oxygen (O₂) to body tissues and remove carbon dioxide (CO₂) from them.
Key Features of Lung Design:
1. Branching Structure:
• The lungs begin with the trachea (windpipe) which branches into:
o Bronchi → Bronchioles → Alveoli (tiny air sacs)
• This highly branched structure increases surface area many times.
2. Alveoli (Air Sacs):
• Lungs contain 300–400 million alveoli.
• Alveoli are small, balloon-like structures with extremely thin walls.
• These increase the surface area to about 70–100 square meters — roughly the size of a tennis court!
3. Thin Walls:
• Alveolar walls and capillaries are one cell thick, allowing for easy diffusion of gases.
4. Rich Blood Supply:
• Alveoli are surrounded by a dense network of capillaries.
• This maintains a constant concentration gradient:

 

15. Why is it Necessary to Separate Oxygenated and Deoxygenated Blood in Mammals and Birds? -

ANSWER= Mammals and birds are warm-blooded (endothermic) animals, which means they maintain a constant and high body temperature, regardless of the surrounding environment. This requires a high amount of energy, which in turn demands an efficient supply of oxygen to body cells for respiration.
Separation of oxygenated and deoxygenated blood in mammals and birds ensures efficient oxygen delivery, supports high metabolic demands, and helps maintain constant body temperature—essential for survival in varied environments.

 

16. What are the components of the transport system in highly organised plants? -

ANSWER= In highly organised (vascular) plants, there are two main components responsible for the transport of water, minerals, and food:
1. Xylem – Transport of Water and Minerals
• Function: Conducts water and dissolved minerals from the roots to all parts of the plant (mainly upwards).
• Components:
o Tracheids and Vessels (main conducting elements)
o Xylem parenchyma (storage)
o Xylem fibres (support)
• Mechanism:
o Water moves via transpiration pull, capillary action, and root pressure.
2. Phloem – Transport of Food
• Function: Transports prepared food (mainly sucrose) from leaves to other parts of the plant (both upward and downward).
• Components:
o Sieve tubes (main conducting elements)
o Companion cells (assist sieve tubes)
o Phloem parenchyma (storage and lateral transport)
o Phloem fibres (support)
• Mechanism: Translocation – an active process that requires energy (ATP).

 

17. How Are Water and Minerals Transported in Plants? -

ANSWER= Water and minerals are transported in vascular plants primarily through a specialized tissue called the xylem. This process occurs from the roots to the leaves and is mainly unidirectional (upward).
1. Absorption by Roots
• Root hairs absorb water and minerals from the soil via osmosis (for water) and active transport (for minerals).
• This happens in the root epidermis.
2. Movement to Xylem
• Water and minerals move through the cortex and endodermis to reach the xylem vessels in the root.
3. Upward Movement through Xylem
• Xylem vessels act like long tubes conducting water and minerals upward to stems and leaves.
Forces Responsible for Upward Transport:
Force Description
Root Pressure Osmotic pressure in the roots pushes water upward; effective in small plants.
Capillary Action Water rises in narrow xylem vessels due to adhesion and cohesion.
Transpiration Pull Evaporation of water from leaf surfaces creates a suction force pulling water upward; main force in tall plants.

 

18. How is Food Transported in Plants? -

ANSWER= In plants, food (mainly sugars like sucrose) is transported through a specialized tissue called phloem by a process known as translocation
Translocation is the transport of soluble products of photosynthesis (mainly sugars) from the source (leaves) to the sink (storage organs or growing parts like roots, fruits, stems, etc.).
1. Loading of Sugar (at Source – Leaves):
o Sugars formed in leaves are actively loaded into phloem sieve tubes using energy (ATP).
o This creates a high osmotic pressure in that area.
2. Water Follows:
o Water enters the phloem from adjacent xylem by osmosis, creating high pressure.
3. Pressure Flow Mechanism:
o This pressure pushes the phloem sap from source to sink.
o This is known as the Pressure Flow Hypothesis.
4. Unloading at Sink:
o Sugars are actively or passively transported out at the sink (e.g., roots, fruits).
o Water moves out of phloem, reducing pressure