Biology: Enzymes and Cell Processes

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Questions and Answers

What happens to red blood cells when placed in a hypertonic solution?

They undergo hemolysis.

They lose water and become plasmolysed. (correct)

They absorb water and swell.

They remain unchanged.

Why are isotonic drinks recommended for athletes?

They replenish energy immediately.

They provide high levels of protein.

They help balance body fluids. (correct)

They slow down metabolic processes.

How does vinegar preserve mangoes?

It creates a hypertonic environment that attracts moisture.

It increases the pH of the mangoes.

It lowers the pH and hinders decomposition. (correct)

It introduces high levels of sugar.

Which of the following is a characteristic of enzymes?

Enzymes are specific to certain substrates. Signup and view all the answers

What effect does high temperature have on enzyme activity?

It denatures the enzyme, ceasing its function. Signup and view all the answers

What are cofactors in enzymatic reactions?

Metallic ions and vitamins required for enzymatic action. Signup and view all the answers

How do inhibitors affect enzymes?

They change the shape and active sites of the enzyme. Signup and view all the answers

What happens when an enzyme is denatured?

It loses its specific shape and cannot catalyze reactions. Signup and view all the answers

Which of the following is NOT considered a good eating habit?

Eating large quantities of sugary foods Signup and view all the answers

What is a primary health issue linked to obesity?

Hypertension Signup and view all the answers

Which of the following factors is crucial when choosing food for a balanced diet?

The nutritional values of the food Signup and view all the answers

What can excessive intake of fats and carbohydrates lead to?

Excess body weight Signup and view all the answers

Which is a recommended practice for better digestion?

Chewing food properly Signup and view all the answers

Which of the following statements is true regarding obesity?

It can be avoided by exercising regularly Signup and view all the answers

What health problem can arise from irregular meals?

Malnutrition Signup and view all the answers

What is recommended to avoid while maintaining a healthy diet?

Overeating processed foods Signup and view all the answers

What occurs at the optimum temperature of 37°C for enzyme activity?

Enzyme activity is at its highest. Signup and view all the answers

What role does the substrate play in the 'lock and key' hypothesis?

The substrate fits perfectly into the enzyme's active site. Signup and view all the answers

Which factor does NOT affect enzyme activity significantly?

Surface area of the enzyme Signup and view all the answers

What happens to enzymes at very high temperatures?

Enzymes are denatured. Signup and view all the answers

How does increasing temperature initially affect enzyme activity?

It leads to more frequent collisions between enzyme and substrate. Signup and view all the answers

Which statement about enzyme specificity is true?

Each enzyme is specific to a particular substrate. Signup and view all the answers

What is the product of an enzyme-substrate reaction?

The enzyme remains unchanged. Signup and view all the answers

What effect does a decrease in substrate availability have on enzyme activity?

Enzyme activity decreases due to lack of substrate. Signup and view all the answers

What is a key advantage of Ultra Heat Treatment (UHT) of milk?

It kills bacteria and their spores. Signup and view all the answers

What is one disadvantage of using freezing as a food preservation method?

Bacteria and spores are not killed. Signup and view all the answers

What does dehydration or drying achieve in food preservation?

Preservation of flavors, vitamins, and nutrients. Signup and view all the answers

How does irradiation affect food preservation?

It kills microorganisms but may destroy nutrients. Signup and view all the answers

Which of the following methods can preserve food without killing bacteria?

Freezing Signup and view all the answers

What is a benefit of using deep freezing for food storage?

It slows down the growth rate of microorganisms. Signup and view all the answers

Which food preservation method uses gamma rays?

Irradiation Signup and view all the answers

What is a significant disadvantage of UHT treatment?

Change in the taste of the milk. Signup and view all the answers

What is the primary direction of oxygen diffusion during gas exchange in the lungs?

From the alveoli to the blood capillaries Signup and view all the answers

Which of the following is a product of respiration?

Carbon Dioxide Signup and view all the answers

What is the main function of chlorophyll in photosynthesis?

To capture light energy Signup and view all the answers

Which of the following characterizes the relationship in mutualism?

Both species benefit from the interaction Signup and view all the answers

During which process is ATP produced?

Respiration in mitochondria Signup and view all the answers

What is the primary purpose of photosynthesis?

To produce glucose and oxygen Signup and view all the answers

Which statement accurately describes the function of alveoli in the lungs?

They facilitate gas exchange between air and blood Signup and view all the answers

Which statement is true regarding respiration and photosynthesis?

Respiration occurs in all living organisms Signup and view all the answers

Study Notes

Red Blood Cell Haemolysis

Red blood cells haemolyse when placed in hypotonic solutions.
Water moves into the cell via osmosis, causing it to swell and burst.

Isotonic Drinks for Athletes

Isotonic drinks help replenish fluids lost through sweating.
They maintain a balance of body fluids.

Preserving Mangoes with Vinegar

Vinegar's low pH creates an acidic environment inhibiting enzyme, bacteria, and fungi activity.
This slows down decomposition and extends the shelf life of mangoes.

General Characteristics of Enzymes

Enzymes accelerate biochemical reactions by lowering activation energy.
They are not consumed during reactions and can be reused.
Small quantities are highly effective.
They catalyze reversible reactions.
They are denatured at high temperatures (above 40°C).
They are sensitive to pH changes.
Enzyme activity is specific to particular substrates.
Enzyme activity can be affected by inhibitors.
Some enzymes require cofactors (metallic ions and vitamins) to function.

Lock and Key Hypothesis of Enzyme Action

Enzymes have specific active sites that bind to substrates.
Substrates fit into the active site like a key into a lock, forming an enzyme-substrate complex.
The enzyme facilitates the conversion of substrate to product.
The product is released, leaving the active site to catalyze another reaction.

Factors Affecting Enzyme Activity

Temperature: Enzyme activity increases with temperature up to an optimum point (around 37°C for many human enzymes), then decreases due to denaturation at higher temperatures.
pH: Enzymes have an optimal pH range; deviations from this range can decrease activity.

Obesity: Excessive intake of fats and carbohydrates leads to excess body weight, increasing the risk of diabetes, hypertension, and cardiovascular diseases.
Gastritis: Irregular meals and excessive gastric juice secretion can cause gastritis.
High blood cholesterol: often linked to an unbalanced diet.
Colon cancer: Linked to poor diet and slow movement of faeces through the colon.
Haemorrhoids: Associated with poor diet and straining during bowel movements.

Good Eating Habits

Eat three meals a day at regular times.
Consume a balanced, nutritious diet, including ample vegetables and fruits for fiber.
Avoid overeating or undereating.
Limit sugar, spicy, oily, and salty foods.
Drink sufficient water (2-3 liters daily).
Chew food thoroughly.

Food Preservation Methods

Vinegar: Low pH inhibits microbial growth.
UHT (Ultra-High Temperature) Treatment: Heats milk to 132°C for 2 seconds, killing bacteria and spores but altering taste and reducing some vitamins.
Dehydration/Drying: Removes water from the food, inhibiting microbial growth; may alter taste and texture slightly but preserves nutrient value better than UHT.
Freezing/Cooling/Chilling/Refrigeration: Slows microbial growth but doesn't kill bacteria or spores.
Freezing Drying: Combines freezing and dehydration, preserving taste and nutrients effectively while inhibiting microbial growth, but doesn't eliminate them.
Irradiation (gamma rays): Kills microorganisms but can destroy some nutrients and alter taste.

Gaseous Exchange in the Lungs

Oxygen diffuses from the alveoli (higher concentration) into the blood capillaries (lower concentration).
Carbon dioxide diffuses from the blood capillaries (higher concentration) into the alveoli (lower concentration) for expulsion.

Comparison of Photosynthesis and Respiration

Photosynthesis: Occurs in green plants, requires light, uses carbon dioxide and water to produce glucose and oxygen; stores energy; anabolic process.
Respiration: Occurs in all living organisms, uses glucose and oxygen to produce carbon dioxide, water, and energy; releases energy; catabolic process.

Symbiotic Relationships

Commensalism: One species benefits, the other is neither harmed nor benefited. Example: Rafflesia sp (parasite).
Mutualism: Both species benefit. (Example not provided in text.)

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Description

This quiz covers key concepts in biology, focusing on red blood cell haemolysis, the role of isotonic drinks for athletes, and enzyme characteristics. Understand how environmental factors affect cells and the biochemical processes involved in enzyme activity and preservation methods. Test your knowledge on these essential biological topics.