Summer Exam 2026 (Science, v2)

What are the three main physical parts that make up the human circulatory system?

Blood, Blood Vessels (tubes to transport blood), and the Heart (to pump the blood).

What are the four main components of blood?

Plasma, Red Blood Cells, White Blood Cells, and Platelets.

What is the function of Plasma in the blood?

To transport chemicals and substances through dissolution and to distribute heat to maintain a body temperature of $37^\circ\text{C}$.

Where are Red Blood Cells and White Blood Cells produced?

In the bone marrow, which is the soft, jelly-like centre of our bones.

What is the function of Haemoglobin in Red Blood Cells?

It is a red chemical that picks up oxygen, allowing the cells to carry it throughout the body.

How do White Blood Cells fight infection in the body?

They can surround and destroy micro-organisms or produce special protein-based antibodies to destroy them.

What is the primary function of platelets?

To help form blood clots to prevent blood loss.

Why do Arteries have thick, strong walls compared to Veins?

To cope with the strong, high-pressure blood flow as blood is pumped away from the heart.

What feature do Veins have to prevent the backflow of blood under low pressure?

Valves.

How is the structure of a capillary suited to its function of substance exchange?

The walls are extremely thin (only 1 cell thick), allowing substances like oxygen and nutrients to pass in and out easily.

What is the cardiac muscle wall that separates the left and right sides of the heart?

The septum.

What are the four chambers of the heart?

Right Atrium, Left Atrium, Right Ventricle, and Left Ventricle.

What is the specific function of the Left Ventricle?

It pumps oxygenated blood out through the Aorta to all parts of the body.

Which heart chamber is responsible for pumping deoxygenated blood to the lungs?

The Right Ventricle (via the pulmonary artery).

What is meant by 'Double Circulation' in the human circulatory system?

Blood moves through two pathways: one between the heart and lungs, and another between the heart and the rest of the body.

What is the difference between systolic and diastolic blood pressure?

Systolic is the higher pressure recorded when the left ventricle contracts; diastolic is the lower pressure exerted on artery walls in between beats.

What is Cardiology?

The branch of medicine that deals with diseases of the heart and blood vessels.

Rate of reaction

How fast a chemical reaction happens

Requirement for reactions

Reactants must be in contact

Reason contact is needed

Particles must collide to react

Effective collision

A collision with enough energy to form products

Ineffective collision

A collision without enough energy; no reaction

Activation energy

Minimum energy needed for a reaction to start

Reason reactions need activation energy

Particles must reach a certain energy level to react

Collision theory

Reactions occur when particles collide with enough energy

Factors affecting rate

Concentration, temperature, catalysts, surface area

Effect of concentration –

More particles in the same space cause more collisions

Doubling concentration

Doubles the number of collisions

Effect of temperature –

Higher temperature increases particle speed and collision frequency

Temperature and rate

Higher temperature means more effective collisions and faster rate

Catalyst

A substance that lowers activation energy

Effect of catalyst

Provides an alternative pathway with lower activation energy

Catalyst and rate

More effective collisions lead to faster reaction

Example catalyst

Manganese dioxide speeding up hydrogen peroxide decomposition

Surface area effect

Smaller particles increase surface area

Reason surface area increases rate

More collisions occur at the surface

Particle size and rate –

Smaller particles react faster

Marble chips experiment –

Loss of mass shows CO2 production; smaller chips lose mass faster

Temperature experiment –

Higher temperature increases hydrogen gas production

Hydrogen test –

Burns with a pop

Oxygen test –

Relights a glowing splint

Carbon dioxide test –

Extinguishes a flame

Biochemical reaction –

A chemical reaction occurring in living cells

Examples of biochemical reactions –

Respiration, photosynthesis, digestion

Enzyme –

A biological catalyst

Example of an enzyme

Amylase

Factors affecting biochemical reactions –

Enzyme concentration, temperature, pH

Effect of incorrect pH –

Enzymes become inactive

Chemical bond

The force that holds atoms together

Atom

The smallest unit of matter; indivisible

Electron shells

Energy levels where electrons are found

Atomic number

The number of electrons in a neutral atom

Electron energy levels

Electrons have different energies and occupy specific shells

Octet rule

Atoms tend to gain, lose, or share electrons to have 8 in their outer shell

First electron shell

Holds up to 2 electrons

Other electron shells

Hold up to 8 electrons

Why electrons matter

Electron configuration determines bonding behaviour

Electron dot structure

Symbol of an atom with dots showing valence electrons

Chemical bonds purpose

Atoms bond to fill their outer electron shells

Ionic bond

Bond formed by transfer of electrons

Covalent bond

Bond formed by sharing electrons

Metallic bond

Bond between metal atoms involving a sea of electrons

Ionic compound definition

Forms when atoms lose or gain electrons to form ions

Metals in ionic bonding

Lose electrons to match nearest noble gas

Positive ion formation

Occurs when electrons are fewer than protons

Group 1 metals

Form 1+ ions

Group 2 metals

Form 2+ ions

Group 13 metals

Form 3+ ions

Sodium ion formation

Sodium loses 1 electron to form Na+

Magnesium ion formation

Magnesium loses 2 electrons to form Mg2+

Cations examples

H+, Li+, Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, Al3+

Ionic bond characteristics

Between metals and nonmetals; transfer of electrons; high melting point; conduct electricity

Examples of ionic compounds

NaCl, CaCl2, K2O

Ionic bond explanation

One atom steals electrons from another, forming charged ions

Covalent compound formation

Atoms share electrons to fill outer shells

Examples of covalent compounds

O2, CO2, C2H6, H2O, SiC, H2

Covalent bonding example

Two oxygen atoms share electrons to form O2

Fluorine covalent bonding

Two fluorine atoms share electrons so both reach 8 valence electrons

Predicting ratios of elements

Use valence electrons to determine how atoms combine

Reactivity

How easily an element bonds with other elements to form compounds

Reactive elements

Elements that bond easily and are rarely found uncombined in nature

Cause of reactivity

Having an incomplete valence electron level

Rule of octet

Atoms (except hydrogen) want 8 electrons in their outermost energy level

Atoms with few valence electrons

Lose electrons during bonding

Atoms with 6, 7, or 8 valence electrons

Gain electrons during bonding

Alkali metals

Elements in the first column of the periodic table

Valence electrons in alkali metals

1 valence electron

Properties of alkali metals

Shiny, clay‑like, easily cut with a knife

Reactivity of alkali metals

Very reactive metals that do not occur freely in nature

Alkali metals and water

React violently and can explode

Alkali metals in nature

Never found uncombined; always bonded

Hydrogen position

Sits above Group 1 but is not part of the alkali metals

Hydrogen properties

Gas at room temperature; 1 proton and 1 electron

Hydrogen valence shell

Needs only 2 electrons to fill its shell

Transition metals

Metals with brightly coloured compounds used in paints

Transition metals and oxygen

Form oxides

Magnetic transition metals

Iron, cobalt, and nickel

General metal properties

Ductile, malleable, conduct heat and electricity

Rare earth elements

Many are man‑made

Other metals

Ductile, malleable, solid, high density