Science Bio Test

1. Define Metabolism: Metabolism is all the chemical reactions occurring in the cells of a living organism to maintain life.

2. Two Types of Chemical Reactions:

Enzymes

1. What are enzymes? Enzymes are organic catalysts that speed up the rate of a reaction without being used up in the process.

2. How many enzymes are in the human body (approximately)? Over 700

3. Specificity: Enzymes are specific because they have a particular shape that allows them to attach to a specific molecule (reactant molecule) which will be changed by the chemical reaction.

4. Lock and Key Model:

• The Lock and Key model describes how an enzyme's active site has a specific shape that only fits a particular substrate (reactant molecule), like a key fitting into a lock.

• The reactant molecule is the molecule that is going to be changed by the enzyme.

1. Anabolism vs. Catabolism:

• Anabolism builds larger, complex molecules from smaller, simpler ones and requires energy.

• Catabolism breaks down larger, more complex molecules and releases energy.

Getting Nutrients

1. Source of Raw Materials: The body gets its raw materials from food.

2. Role of Enzymes in Digestion: Enzymes are essential in the digestive system because they change the nutrients coming from food into a form that the body can readily use. The digestive system is responsible for getting all the good stuff that we need from our food.

3. Nutrient Breakdown:

• Carbs → glucose

• Proteins → amino acids

• Lipids (fats and oils) → fatty acids and glycerol

Diffusion

1. Define Diffusion: Diffusion is the movement of particles of a substance from an area of high concentration to an area of low concentration.

2. Diffusion in the Intestine: Diffusion helps in the absorption of nutrients because, after eating, there is a high concentration of amino acids, glucose, fatty acids & glycerol in the intestine, but a low concentration in the bloodstream. Diffusion causes these molecules to move from the small intestine into the blood capillaries.

Oxygen

1. Pathway of Air: Air enters through the nose and mouth, moves down the trachea, bronchi, and bronchioles, before ending in the alveoli.

2. Gas Exchange: Oxygen diffuses into the bloodstream across the thin walls of the alveoli, surrounded by blood capillaries.

Oxygen in the Blood

1. Oxygen Transport: Oxygen combines with haemoglobin in red blood cells.

2. Why does diffusion continue to take place in the alveoli? Diffusion continues to take place as the oxygen is being carried off by the blood, there is always lower concentration of oxygen just outside the alveoli.

Circulation

1. Components of the Circulatory System: Arteries, capillaries, and veins

2. Function of the Circulatory System: The system carries materials to and from EVERY cell in your body.

3. Role of the Heart: The heart is the pump that keeps the blood moving throughout the circulatory system, as it contracts and relaxes.

4. Pacemaker: The pacemaker (SA node) is what initiates your heartbeat.

Heart Rate

1. Control of Heart Rate: The heart rate (HR) is controlled by the autonomic NS (involuntary).

2. Factors Affecting Heart Rate:

• Exercise: Heart rate will increase so more oxygen can get to your muscles.

• Stress or Fear: Heart rate will also increase (hormonal action, the hormone produced is noradrenaline.)

Review Questions

(Answers will vary based on textbook and workbook content)

Glossary Terms

• Endothermic: Able to maintain a constant body temperature

• Metabolism: All the chemical reactions occurring in the cells

• Catalyst: A substance that speeds up the rate of a reaction without being used up in the process

• Diffusion: The movement of particles of a substance from an area of high concentration to an area of low concentration

• Enzyme: An organic (comes from living things) catalyst

• Mitochondria: Organelles where cellular respiration occurs

• Reactant Molecule: The molecule that is going to be changed by a chemical reaction

• Ribosome: The organelle where proteins are manufactured