Life Processes-Exercise
Biology - Exercise
Q1. The kidneys in human beings are a part of the system for
- nutrition.
- excretion.
- respiration.
- transportation.
Q2. The xylem in plants are responsible for
- transport of water.
- transport of food.
- transport of amino acids.
- transport of oxygen.
Q3. The autotrophic mode of nutrition requires
- carbon dioxide and water.
- chlorophyll.
- sunlight.
- all of the above.
- cytoplasm.
- mitochondria.
- chloroplast.
- nucleus.
Q5. How are fats digested in our bodies? Where does this process take place?
Fats are first emulsified by bile from the liver, which breaks them into smaller droplets. Then, pancreatic lipase digests these droplets into glycerol and fatty acids. This entire process takes place in the small intestine.
Q6. What is the role of saliva in the digestion of food?
Saliva plays an important role in digestion by moistening and lubricating food, making it easier to chew and swallow. It contains the enzyme salivary amylase, which begins the breakdown of starch into maltose. Saliva also helps in tasting food and maintaining oral hygiene.
Q7. What are the necessary conditions for autotrophic nutrition and what are its by products?
-
Necessary conditions for autotrophic nutrition:
- Carbon dioxide \((CO_2)\): as a source of carbon.
- Water \((H_2O)\)required for photosynthesis.
- Chlorophyll: to capture sunlight energy.
- Sunlight: as the energy source for synthesizing food.
-
By products:
- Oxygen \((O_2)\): released into the atmosphere.
- Glucose \((C_6H_{12}O_6)\): produced as food for the plant.
Q8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.
Differences between Aerobic and Anaerobic Respiration:
| Aerobic Respiration | Anaerobic Respiration |
|---|---|
| Aerobic respiration requires oxygen | Anaerobic respiration occurs without oxygen |
| Aerobic respiration produces carbon dioxide, water, and a large amount of energy (ATP) | anaerobic respiration produces alcohol/ lactic acid, carbon dioxide, and less energy. |
| Aerobic respiration releases much more energy | Anaerobic respiration releases less energy |
| Aerobic respiration occurs in the mitochondria | Anaerobic respiration occurs in the cytoplasm. |
Q9. How are the alveoli designed to maximise the exchange of gases?
The alveoli in the lungs are carefully adapted to maximize gas exchange by providing a large, thin, and moist surface closely surrounded by capillaries, which ensures efficient diffusion of oxygen and carbon dioxide
-
Key Adaptations of Alveoli
- Alveoli are extremely numerous (about 700 million in both lungs), creating a huge surface area for gas exchange to occur, which increases the rate at which oxygen and carbon dioxide can diffuse
- Their walls are just one cell thick, minimizing the diffusion distance and enabling rapid movement of gases between air and blood.
- They are surrounded by a dense network of capillaries, ensuring a rich blood supply to maintain a concentration gradient for oxygen and carbon dioxide between alveolar air and blood.
- The inner surfaces of alveoli are coated with a thin film of fluid, allowing gases to dissolve before diffusing across the cell membrane—this moisture is crucial for efficient diffusion.
- Alveoli are lined with two types of cells: Type I cells (making up most of the surface and forming the thin barrier), and Type II cells (which produce surfactant to reduce surface tension and prevent alveolar collapse during breathing).
-
Concentration Gradient and Gas Exchange
- Ventilation (breathing) constantly supplies oxygen-rich air and removes carbon dioxide, maintaining steep concentration gradients.
- Oxygen diffuses from the alveoli (where the concentration is higher) into the blood (where it's lower), while carbon dioxide moves from the blood to the alveoli for exhalation.
These specialized features enable the alveoli to efficiently exchange oxygen and carbon dioxide, ensuring cells in the body receive the oxygen they need and can remove waste carbon dioxide.
Q10. What would be the consequences of a deficiency of haemoglobin in our bodies?
A deficiency of haemoglobin in the body decreases the blood’s capacity to transport oxygen, leading to reduced oxygen supply to the body’s tissues and organs. This results in symptoms like tiredness, weakness, shortness of breath, and paleness, and can cause a condition called anaemia
- Haemoglobin is the respiratory pigment in red blood cells that carries oxygen from the lungs to the rest of the body.
- If haemoglobin is deficient, less oxygen reaches body cells, which slows down cellular respiration and energy production.
- This causes tiredness, weakness, pale appearance, and lack of energy, making it hard to perform physical tasks.
- Severe deficiency causes anaemia, which may result in shortness of breath, dizziness, and faster heartbeat as the body tries to compensate for low oxygen.
In summary, adequate haemoglobin is essential for normal energy levels, a healthy appearance, and proper functioning of the body’s organs and tissues.
Q11. Describe double circulation of blood in human beings. Why is it necessary?
In human beings, double circulation means that blood passes through the heart twice during one complete cycle in the body. This system includes two main circulations: pulmonary circulation (between the heart and lungs) and systemic circulation (between the heart and the rest of the body)
-
Description of Double Circulation
- The right side of the heart receives deoxygenated blood from different parts of the body and pumps it to the lungs, where it receives oxygen (pulmonary circulation).
- The oxygenated blood returns to the left side of the heart, which then pumps it to all body organs and tissues (systemic circulation).
- Thus, blood flows through the heart twice—once to get oxygen from the lungs and again to deliver that oxygen to the body.
-
Necessity of Double Circulation
- Double circulation keeps oxygen-rich and oxygen-poor blood completely separate, preventing their mixing.
- This ensures a consistent and efficient supply of oxygenated blood to all body cells, supporting the high energy needs in humans.
- It also allows for higher blood pressure in the systemic circulation, ensuring nutrients and oxygen reach even distant tissues effectively.
Double circulation is essential for providing pure, oxygen-rich blood to body tissues and for removing carbon dioxide efficiently, supporting healthy life processes in humans.
Q.12 What are the differences between the transport of materials in xylem and phloem?
| Difference between Xylem and Phloem | ||
|---|---|---|
| Feature | Xylem | Phloem |
| Main Transport | Water and minerals | Food (sugars, nutrients) |
| Direction | Only upward (roots to shoots/leaves) | Both upward and downward |
| Cell Types | Mostly dead, lignified cells | Living cells (sieve tubes, companions) |
| Energy Requirement | Passive (no energy needed) | Active (energy needed) |
Q13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning
| Aspect | Alveoli (Lungs) | Nephron (Kidneys) |
|---|---|---|
| Structure | Thin-walled, sac-like, many in cluster, surrounded by capillaries | Long tubule with filtering (glomerulus) and reabsorption sections, surrounded by capillaries |
| Main function | Exchange of oxygen and carbon dioxide between air and blood | Removal of waste products from blood, and regulation of water and salt balance |
| Exchange type | Rapid gas diffusion | Filtration and selective reabsorption, secretion |
| Contact with blood | Direct with capillaries (for rapid gas transfer) | Capillary network around glomerulus and tubule (for filtration and reabsorption) |
Summary: while both alveoli and nephrons are specialized for exchange with the bloodstream, alveoli are adapted for fast gas exchange to support respiration, and nephrons for filtering and maintaining the chemical balance of body fluids as part of excretion.
