Paper 1 and 2 Biology

What are the main differences between animal and plant cells?

• Animal: nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

• Plant: all of the above + cell wall, chloroplasts, permanent vacuole

What is the difference between eukaryotic and prokaryotic cells?

• Eukaryotic: nucleus present (animals, plants)

• Prokaryotic: no nucleus, DNA in cytoplasm (bacteria)

What is cell differentiation?

The process by which a cell changes to become specialised for its function.

What is cell specialisation?

When cells have specific structures to carry out a particular function.

What is magnification?

How much bigger the image is compared to real size.

Equation for magnification?

Magnification = image size ÷ real size

What is mitosis?

Cell division producing two genetically identical daughter cells.

What is the cell cycle?

Growth → DNA replication → mitosis

What are stem cells?

Undifferentiated cells that can become different cell types.

What is diffusion?

Movement of particles from high to low concentration.

What is osmosis?

Movement of water across a partially permeable membrane from dilute to concentrated solution.

What is active transport?

Movement of substances from low to high concentration using energy.

Levels of organisation in multicellular organisms?

Cells → tissues → organs → organ systems

What do enzymes do?

Act as biological catalysts (speed up reactions).

What affects enzyme activity?

Temperature, pH, substrate concentration.

What are the main blood vessels?

Arteries, veins, capillaries.

Function of arteries?

Carry blood away from the heart.

Function of veins?

Carry blood to the heart.

Function of capillaries?

Exchange of substances.

What does the heart do?

Pumps blood around the body.

What is coronary heart disease (CHD)?

Narrowing of coronary arteries reducing blood flow.

Examples of non-communicable diseases?

Cancer, CHD.

What is transpiration?

Loss of water from leaves.

Factors affecting transpiration?

Light, temperature, air flow, humidity.

What is a communicable disease?

Disease that can be spread.

Types of pathogens?

Virus, bacteria, fungi, protists.

How do viruses reproduce?

Inside host cells.

How do bacteria reproduce?

Binary fission.

What are the body’s defences?

Skin, mucus, immune system.

What is vaccination?

Introducing small amounts of pathogen to trigger immunity.

What do antibiotics do?

Kill bacteria (not viruses).

Word equation for photosynthesis?

Carbon dioxide + water → glucose + oxygen

What are limiting factors of photosynthesis?

Light intensity, CO₂ concentration, temperature.

Word equation for aerobic respiration?

Glucose + oxygen → carbon dioxide + water

What is anaerobic respiration (animals)?

Glucose → lactic acid

What is anaerobic respiration (plants/yeast)?

Glucose → ethanol + carbon dioxide

What is metabolism?

All chemical reactions in the body.

What is homeostasis?

Regulation of internal conditions to maintain optimum conditions.

What hormone lowers blood glucose?

Insulin.

What hormone raises blood glucose?

Glucagon.

What does insulin do?

Moves glucose into cells and stores it as glycogen in the liver.

What does glucagon do?

Converts glycogen into glucose.

What happens when body temperature is too high?

Sweating and vasodilation.

What happens when body temperature is too low?

Shivering and vasoconstriction.

What is a reflex action?

Rapid, automatic response.

Pathway of a reflex?

Receptor → sensory neurone → relay neurone → motor neurone → effector

What does Follicle-Stimulating Hormone (FSH) do?

Matures an egg.

What does Luteinising Hormone (LH) do?

Triggers ovulation.

What does oestrogen do?

Thickens uterus lining.

What does progesterone do?

Maintains uterus lining.

What is a gene?

Section of DNA coding for a protein.

What is an allele?

Different version of a gene.

Dominant allele?

Always expressed.

Recessive allele?

Only expressed if two copies.

What is an ecosystem?

Interaction between living and non-living factors.

What is a food chain?

Shows feeding relationships.

What is a food web?

Interconnected food chains.

Biotic factors?

Living factors (predators, disease)

Abiotic factors?

Non-living (light, temperature, water)

Which two systems in the body control homeostasis?

The nervous system and the hormonal (endocrine) system.

What is the role of a receptor in the body?

Receptors in organs detect changes in internal or external environment (stimuli).

What is the function of a coordination centre, and give 3 examples?

A coordination centre processes information. E.g. brain, spinal cord and pancreas.

Describe the role of an effector.

Effectors are organs (muscles or glands) that respond to a stimulus to bring about a change in the body.

What organs make up the Central Nervous System (CNS)?

brain and spinal cord.

Describe the sequence of events in a nervous response, starting from the stimulus.

Stimulus → Receptor →Coordinator (CNS) → Effector → Response

How is information sent between the receptors and the coordination centres?

Via hormones or nervous impulses.

Nerve

Bundle of nerve cells.

Job of nerves.

Carry electrical signals.

Reflex

Automatic, fast response

Purpose of reflex

Protects you from harm E.g. Knee jerk, blinking

Synapse

Gap between nerves

How signal crosses

Chemical crosses gap

Reaction Time Test

Step 1: Hold ruler above thumb

Step 2: Drop it without warning

Step 3: Catch it as fast as you can

Step 4: Measure where caught

Slow reaction: Bigger number

Fast reaction: Smaller number

Independent Variable

What you change

Dependent Variable

What you measure

Control Variable

Keep the same

Glands

Release hormones

How do Glands travel?

Hormones go into blood

Speed of Glands

Slower than nerves

Duration of Glands

Lasts longer

Effect of Glands

Affects the whole body

What organ controls blood sugar?

Pancreas

What happens if sugar is too high?

Insulin is released

What does insulin do?

Turns glucose into glycogen

What organ does glucose get stored in?

Liver

What is Type 1 Diabetes?

Not enough insulin

Treatment for Type 1 Diabetes

Injections

What is Type 2 Diabetes?

Cells don’t respond to insulin

Treatment for Type 2 Diabetes

Diet + exercise

Risk factor for Type 2 Diabetes

Being overweight

What is contraception?

Stops pregnancy

What does contraception control?

Controls fertility

What is sexual reproduction?

2 parents, mixing DNA

What is Asexual reproduction?

1 parent, identical copy

What is meiosis?

Makes Gametes (sex cells)

What is a genome?

All the DNA

What is a gene?

Small part of DNA

What is an allele?

Different version of a gene

What is genotype?

Genes you have