GCSE Biology Topic 2

Define 'tissue'.

A group of cells with similar structure working together for a specific function

Define 'organ'.

A group of tissues working together for specific functions

Reorder the following in increasing size order: Organ, cell, tissue, organ system, organism

Cell < Tissue < Organ < Organ system < Organism

State the function of the salivary glands.

Produce digestive enzymes (eg. Amylase)

Name the tube that carries food from the mouth to the stomach.

Oesophagus/Gullet

State the function of the stomach.

Releases digestive enzymes to digest food

State the function of the liver in the digestive system.

Produces bile for lipid digestion

State the function of the small intestine.

Digest food and absorb nutrients from digested food

State the function of the large intestine.

Absorb water from digested food

State the the function of the pancreas.

Produces/Releases digestive enzymes

State the function of the gall bladder.

Store bile before release into small intestine

What are carbohydrates made up of?

Simple sugars

State the chemical formula of glucose.

C6H12O6

Name a complex carbohydrate that is made up of glucose.

Starch/Cellulose/Glycogen

State the importance of having carbohydrates in our diet.

Energy source - Break down glucose in respiration to release energy for metabolic reactions

What elements make up carbohydrates?

C, H, O

What are lipids made up of?

1 glycerol + 3 fatty acids

State the importance of having lipids in our diet.

Energy store/Make up cell membranes/Steroid hormones

What elements make up lipids?

C, H, O

What are proteins made up of?

Amino acids

State the importance of having proteins in our diet.

Structural components/Hormones/Antibodies/Enzymes

What elements make up proteins?

C, H, O, N

Name the reagent used to test for starch.

Iodine

What is a positive result for starch test?

Starch turns iodine from brown-red to blue-black

Name the reagent used to test for sugars.

Benedict's solution

What is the positive result for sugars?

Benedict's solution turn from clear blue to brick-red (precipitate)

What is the reagent used to test for proteins?

Biuret solution

What is the positive result for proteins?

Biuret turns from blue to purple

What is the reagent used to test for lipids?

Ethanol (+water)

What is the positive test for lipids?

White milky layer

State a hazard in doing food tests.

Ethanol is flammable/Biuret is corrosive

Define 'catalyst'.

A substance that speeds up chemical reactions but don't get used up

Define 'enzyme'.

Biological catalysts that speed up chemical reactions

What kind of molecule are enzymes - carbohdyrates, lipids or proteins?

Proteins

Define 'active site'.

The site on an enzyme where the substrate binds

Any substance can fit into the active site of an enzyme. True or false?

FALSE

Briefly describe the lock- and-key model.

Substrate fits into the active site to form enzyme-substrate complex --> Reaction occurs --> Enzyme releases products and binds to another substrate

Define 'metabolism'.

Sum of all reactions in a cell/body

Define 'denaturation'.

Loss of active site

How does temperature affect enzymes' rate of reaction?

As temp increases, RoR increases until after optimum

Why do enzymes stop working past their optimum temperature?

Denatured (substrate can no longer bind to active site)

Why do enzymes not work well at lower temperatures?

Inactive (not enough KE to collide and bind to active site)

How does a change in pH affect enzyme structure?

pH change affects forces holding enzyme structure together, causing it to denature

Define ' digestion'.

Breakdown of large insoluble molecules into smaller soluble substances

Name the type of enzyme that digests carbohydrates.

Carbohydrases

Name the enzyme that digests starch.

Amylase

Name the product of the breakdown of starch.

Simple sugars

Name the type of enzyme that digests proteins.

Proteases

Name the protease that works well in the stomach.

Pepsin

Name the product of the breakdown of proteins.

Amino acids

Name the type of enzyme that digests lipids.

Lipases

Name the products of the breakdown of lipids.

Glycerol and fatty acids

Which organs produce amylase?

Salivary glands and pancreas

Which organs produce proteases?

Stomach, pancreas, small intestine

Which organs produce lipases?

Pancreas and small intestine

Where does starch digestion occur?

Mouth + Small intestine

Where does protein digestion occur?

Stomach + Small intestine

Where does lipid digestion occur?

Small intestine

How are the nutrients carried away from the gut?

Absorbed into bloodstream through small intestine

State an observation to determine when the amylase has completed its digestion of starch.

Iodine remains brown-red rather than turning blue-black

State a reason for setting the amylase solution, starch solution and the buffer in the water bath before the experiment.

To ensure all of the same temp, so that temp will not affect the results (fair test)

How does the hydrochloric acid in the stomach help with digestion?

Provides optimum pH for pepsin to digest proteins

Apart from digestion, what is another function of hydrochloric acid in the stomach?

Kill pathogens in food

How is the stomach adapted to protect itself from the hydrochloric acid?

Thick mucus layer/quick renewal of epithelial layer

State the two functions of bile.

Emulsifies fats + Neutralises food from stomach (HCl)

What is emulsification?

Physically breaking down large oil drops into smaller droplets, increasing surface area for lipases to work on

Bile is an enzyme. True or false?

FALSE

Hydrochloric acid in the stomach breaks down food. True or false?

FALSE - provides optimum pH for pepsin and kills bacteria, NOT digest food

State the importance of the neutralising role bile has.

Small intestine does not have protective mucus layer + Enzymes will denature in small intestine

What is plasma in the blood?

Yellow liquid that carries blood cells, proteins and dissolved substances around the body

What are red blood cells?

Biconcave cells that have haemoglobin - carry oxygen

Name the pigment found in red blood cells that binds to oxygen.

Haemoglobin

Which organ system transports substances to and from body cells?

Circulatory system

State the functions of white blood cells.

Engult pathogens, produce antibodies and antitoxins

How does being biconcave help red blood cells with their function?

Increase SA:V for efficient diffusion

How is not having a nucleus good for red blood cells?

More space to pack more haemoglobin

State the function of platelets.

Blood clotting

Name the blood vessel type that carries blood from the heart to other parts of the body.

Artery

Name the blood vessel type that carries blood from the organs back to the heart.

Vein

Name the blood vessel type that is found within organs that link arteries and veins.

Capillaries

State a structural difference between arteries and veins.

A: thicker walls, more elastic tissue, no valves; V: thinner walls, less elastic tissues, have valves

State a difference in the blood flowing in arteries and veins.

A: oxygenated, more nutrients, less wastes; V: deoxygenated, less nutrients, more wastes

The flow of blood in veins relies on ..................

Skeletal muscle contraction

Why can substances diffuse easily between capillaries and the cells?

Thin capillary walls (one cell thick)

What is the double circulatory system?

One part carries blood between heart and lungs; the other carries blood between heart and other organs

Name the vessels that supply oxygen to the heart muscles.

Coronary arteries

Name the large vessel that brings deoxygenated blood back into the heart.

Vena cava

Name the upper chambers of the heart.

Atria

Name the lower chambers of the heart.

Ventricles

Name the vessel that brings deoxygenated blood from the heart to the lungs.

Pulmonary artery

Name the vessel that brings oxygenated blood from the lungs to the heart.

Pulmonary vein

Which side of the heart has deoxygenated blood - right or left?

Right

Describe the flow of blood as atria of the heart contract.

Blood flows from atria down to ventricles

Name the large vessel that brings oxygenated blood out of the heart to the body.

Aorta

Why is the muscle wall of the left ventricle thicker than the right ventricle?

To generate more pressure to force blood all over the body (left side only to lungs)

What is the function of heart valves?

Prevent backflow of blood

Name a method to unblock a coronary artery in the heart.

Stent

Name a drug that reduces blood cholesterol levels.

Statins

What can be used to replace a damaged heart valve?

Biological or mechanical valves

What is a natural pacemaker?

A group of cells in the right atrium that controls the resting heart rate