Biology

Question 1

Explain the significance of a balanced diet in maintaining overall health and well-being.

Answer 1

A balanced diet provides essential nutrients for energy, growth, repair, and disease prevention, supporting overall health.

Question 2

Identify and describe the primary functions of the main nutrients required in a balanced diet.

Answer 2

Carbohydrates: Provide energy by being broken down into glucose, support energy storage, and are involved in building macromolecules.
Proteins: Build, maintain, and repair body tissues; act as enzymes and hormones; provide structural support to cells and tissues.
Fats: Source of energy, protect organs, support cell growth, help absorb certain vitamins, and provide insulation.
Vitamins: Support immune function, aid in blood clotting, improve eyesight, and help in various metabolic processes.
Minerals: Build strong bones and teeth, support muscle contraction, and play roles in various bodily functions.
Fiber: Aids in digestion by promoting bowel movements and preventing constipation.
Water: Regulates body temperature, removes waste through urine, and aids in digestion and nutrient absorption.

Question 3

What are monosaccharides, and how do they differ from polysaccharides? Provide examples of each.

Answer 3

Monosaccharides: Simple sugars (e.g., glucose)
Polysaccharides: Complex carbs (e.g., starch, glycogen)

Question 4

Describe the roles of starch, glycogen, and cellulose in plants and animals. How do their structures support their functions?

Answer 4

Starch: Energy storage in plants
Glycogen: Energy storage in animals
Cellulose: Structural support in plants

Question 5

What are the building blocks of proteins, and how are they linked together to form larger protein structures?

Answer 5

Amino acids linked by peptide bonds form polypeptides, which fold into proteins.

Question 6

Discuss the different functions of proteins in the human body, providing examples of each function.

Answer 6

Structural support: Proteins like collagen provide structure to tissues like skin and bones.
Enzymes: Proteins such as amylase catalyze biochemical reactions.
Hormones: Insulin is a protein that regulates blood sugar levels.
Transport: Hemoglobin, a protein, transports oxygen in the blood.
Defense: Antibodies are proteins that help the immune system fight off infections.

Question 7

Why are lipids insoluble in water, and how does this property affect their role in biological systems?

Answer 7

Lipids are insoluble in water because they are non-polar molecules, meaning they do not interact well with water’s polar molecules. This property allows lipids to form cell membranes, which create a barrier that separates the cell’s interior from the external environment. It also enables lipids to store energy efficiently without interfering with the cell’s aqueous environment.

Question 8

Describe the roles of vitamins in maintaining health, and give specific examples of vitamins and their functions.

Answer 8

Vitamin A: Vision
Vitamin C: Collagen synthesis, immunity
Vitamin D: Calcium absorption
Vitamin K: Blood clotting
Vitamin E: Antioxidant

Question 9

Why are minerals important for building strong bones and teeth? Provide examples of key minerals involved in this process.

Answer 9

Calcium and Phosphorus: Bone/teeth strength
Magnesium: Regulates calcium

Question 10

List and explain at least three functions of water in the human body and discuss why adequate hydration is crucial for health.

Answer 10

Temperature regulation: Sweating
Waste removal: Urine
Digestion: Digestive juices

Question 11

Define macromolecules and explain their significance in living organisms. Provide examples of the four major types of macromolecules.

Answer 11

Large molecules essential for life: Carbohydrates, Proteins, Lipids, Nucleic acids.

Question 12

What is the relationship between monomers and polymers in biological macromolecules? Use carbohydrates, proteins, and lipids to illustrate your explanation.

Answer 12

Monomers: Building blocks (e.g., glucose, amino acids, glycerol + fatty acids)
Polymers: Chains of monomers (e.g., starch, polypeptides, triglycerides)

Question 13

What are the steps in preparing a food sample for testing?

Answer 13

Break up the food using a pestle and mortar.
Transfer to a test tube and add distilled water.
Mix the food with the water by stirring with a glass rod.
Filter the mixture using a funnel and filter paper, collecting the solution.
Proceed with the food tests.

Question 14

What reagent is used to test for glucose?

Answer 14

Benedict’s solution.

Question 15

How long do you heat the Benedict’s solution and food sample in a boiling water bath?

Answer 15

5 minutes.

Question 16

What is the positive test color change for glucose using Benedict’s solution?

Answer 16

From blue to orange/brick red.

Question 17

What reagent is used to test for starch?

Answer 17

Iodine solution.

Question 18

What is the positive test color change for starch using iodine?

Answer 18

From orange-brown to blue-black.

Question 19

What solution is used to test for protein?

Answer 19

Biuret solution (sodium hydroxide followed by copper (II) sulphate).

Question 20

What is the positive test color change for protein using Biuret solution?

Answer 20

From blue to violet/purple.

Question 21

What is the first step in testing for lipids?

Answer 21

Mix the food sample with 4 cm³ of ethanol and shake.

Question 22

After mixing the food sample with ethanol, what should you do next?

Answer 22

Strain the ethanol solution into another test tube.

Question 23

What do you add the ethanol solution to in the lipid test?

Answer 23

An equal volume of cold distilled water (4 cm³).

Question 24

What indicates a positive test for lipids?

Answer 24

A cloudy emulsion forming.

Question 25

What are enzymes?

Answer 25

Enzymes are proteins that act as biological catalysts to speed up the rate of a chemical reaction without being changed or used up in the reaction.

Question 26

Why are enzymes necessary for all living organisms?

Answer 26

They allow all metabolic reactions to occur at a rate that can sustain life.

Question 27

What forms when a substrate moves into the enzyme’s active site?

Answer 27

The enzyme-substrate complex.

Question 28

What happens to the enzyme after the reaction has occurred?

Answer 28

The products leave the enzyme’s active site, which is then free to take up another substrate.

Question 29

What happens if the pH is too high or too low for an enzyme?

Answer 29

The bonds that hold the amino acid chain together can be destroyed, changing the shape of the active site, and reducing the rate of activity.

Question 30

What happens to enzymes at high temperatures beyond the optimum?

Answer 30

The bonds that hold the enzyme together break, and the enzyme loses its shape - this is known as denaturation.

Question 31

What is the primary function of the plant leaf?

Answer 31

The primary function of the plant leaf is to perform photosynthesis, which involves making food (glucose) for the plant and releasing oxygen into the atmosphere.

Question 32

How do leaves contribute to photosynthesis?

Answer 32

Leaves absorb carbon dioxide from the air and combine it with water absorbed through the roots to produce glucose, releasing oxygen as a byproduct.

Question 33

What is photosynthesis?

Answer 33

Photosynthesis is an endothermic reaction where green plants use energy from sunlight to convert carbon dioxide and water into glucose and oxygen.

Question 34

Define autotrophs and producers in the context of photosynthesis.

Answer 34

Autotrophs are organisms that can make complex molecules like glucose from simple molecules. Producers are organisms that produce their own food, serving as the base of food chains. Examples include plants and algae.

Question 35

What is the word equation for photosynthesis?
What is the balanced chemical equation for photosynthesis?

Answer 35

Carbon dioxide + Water → Glucose + Oxygen
6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

Question 36

What are the three main limiting factors of photosynthesis?

Answer 36

Temperature, light intensity, and carbon dioxide concentration.

Question 37

How does temperature affect the rate of photosynthesis?

Answer 37

Temperature affects the kinetic energy of molecules and enzyme activity. Low temperatures slow down reactions, while high temperatures can denature enzymes, both of which reduce the rate of photosynthesis.

Question 38

Why do plants need glucose aside from energy?

Answer 38

Plants use glucose to produce starch for storage, synthesize lipids for seeds, form cellulose for cell walls, and produce amino acids for proteins, supporting growth and development.

Question 39

What type of organism is yeast and under which kingdom is it classified?

Answer 39

Yeast is a single-celled organism classified under the kingdom Fungi. It is widely used in baking, brewing, and scientific research due to its fermentation capabilities.

Question 40

Why is yeast considered a eukaryote?

Answer 40

Yeast is considered a eukaryote because it has a true nucleus containing its genetic material (DNA) and membrane-bound organelles such as mitochondria and Golgi apparatus, which are characteristic features of eukaryotic cells.

Question 41

What is a prokaryote and give an example?

Answer 41

A prokaryote is an organism whose cells lack a nucleus and membrane-bound organelles. Prokaryotic cells have their genetic material free-floating in the cytoplasm. An example of a prokaryotic organism is bacteria, like Escherichia coli.

Question 42

Functions of parts of a yeast cell: Nucleus, cell wall, mitochondria, cell membrane, cytoplasm, Golgi.

Answer 42

Nucleus-has genetic material (DNA).
Cell wall-protects the cell from rapid changes in external osmotic potential.
Mitochondria-for aerobic respiration(produce energy for the cell)
Cell membrane-controls movement of materials in and out of the cell.
Cytoplasm-where enzymes and other proteins are made.Also where chemical reactions like anaerobic respiration takes place.
Golgi apparatus-modify and sort newly synthesized proteins to be used outside the cell.

Question 43

What is ATP and why is it important for cells?

Answer 43

ATP (adenosine triphosphate) is a high-energy molecule that cells use to perform work. It is vital for cellular activities such as muscle contraction, nerve transmission, active transport, and chemical synthesis. Cells produce ATP through respiration processes.

Question 44

How do yeast cells produce ATP in the presence of oxygen?
How do yeast cells produce ATP in the absence of oxygen?

Answer 44

In the presence of oxygen, yeast cells use carbohydrates (sugars) to produce ATP, with carbon dioxide and water as by-products. This is called aerobic respiration.
In the absence of oxygen, yeast cells use carbohydrates (sugars) to produce ATP, with carbon dioxide and ethanol as by-products. This is called anaerobic respiration.

Question 45

What is the word equation for aerobic respiration in yeast?
What is the chemical equation for aerobic respiration in yeast?

Answer 45

Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP)
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP)

Question 46

What is the word equation for anaerobic respiration in yeast?
What is the chemical equation for anaerobic respiration in yeast?

Answer 46

Glucose → Ethanol + Carbon dioxide + Energy (ATP)

C6H12O6 → 2 C2H5OH + 2 CO2 + energy (ATP)

Question 47

What is cellular respiration?

Answer 47

respiration is the process by which living organisms take in oxygen and release carbon dioxide, producing energy in the form of ATP from glucose or other organic molecules.

Question 48

What is the difference between photosynthesis and cellular respiration?

Answer 48

Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product. Cellular respiration converts oxygen and glucose into water and carbon dioxide. Water and carbon dioxide are by-product and ATP is energy that is transformed from the process.