Biology: Respiration, Gas Exchange, and Circulatory System

Aerobic respiration word equation

glucose + oxygen → carbon dioxide + water (+ energy)

Where does aerobic respiration occur in cells?

mitochondria of all animal and plant cells

Do all living things respire?

Yes, all living things respire

Process of anaerobic respiration (animals)

glucose → lactic acid (+ some energy)

Process of anaerobic respiration (yeast/plants)

glucose → ethanol + carbon dioxide (+ some energy)

Compare aerobic and anaerobic: oxygen use

Aerobic uses oxygen; anaerobic does not

Compare aerobic and anaerobic: energy released

Aerobic releases more energy; anaerobic releases less

Compare aerobic and anaerobic: products (animals)

Aerobic: CO₂ + H₂O; Anaerobic: lactic acid

Structure of the lungs (pathway)

trachea → bronchi → bronchioles → alveoli

Mechanism of ventilation

diaphragm and intercostal muscles change thoracic volume/pressure

Model lung: what does the rubber sheet represent?

diaphragm

Model lung: what happens when rubber sheet is pulled down?

balloons (lungs) inflate (air enters)

Alveoli adaptations for gas exchange

large surface area, thin walls (one cell thick), good blood supply

Movement of gases at alveoli

oxygen diffuses into blood; carbon dioxide diffuses into alveoli

Inhaled vs exhaled air: oxygen content

inhaled ~21%, exhaled ~16%

Inhaled vs exhaled air: carbon dioxide content

inhaled ~0.04%, exhaled ~4%

Inhaled vs exhaled air: water vapour

exhaled air contains more water vapour

Role of blood in transport

carries oxygen and glucose to cells; carries carbon dioxide away from cells

Four main components of blood

red blood cells, white blood cells, platelets, plasma

Function of red blood cells

carry oxygen

Adaptations of red blood cells (3)

no nucleus, biconcave shape, contains haemoglobin

Function of white blood cells

fight infection

Function of platelets

blood clotting

Function of plasma

liquid transport (carries dissolved substances)

Why do cells and tissues need a good circulatory system?

to efficiently supply oxygen/nutrients and remove waste products

Double circulatory system description

blood passes through heart twice: heart → lungs → heart → body

Artery structure and function

thick muscular wall, small lumen, carries blood AWAY from heart

Vein structure and function

thin wall, large lumen, has valves, carries blood TO heart

Capillary structure and function

one cell thick wall, allows exchange of materials

Heart structure: left ventricle wall thickness

thicker than right ventricle (pumps blood to entire body)

Heart structure: function of valves

prevent backflow of blood

Effect of exercise on breathing and heart rates

both increase

Why is increased breathing/heart rate necessary during exercise?

to deliver more oxygen and glucose to muscles and remove extra carbon dioxide

Daphnia investigation: independent variable

drug concentration

Daphnia investigation: dependent variable

heart rate (beats per minute)

Daphnia investigation: control variables

temperature, size of Daphnia, volume of solution

Identify elements, compounds, and mixtures from particle diagrams

element: one type of atom; compound: different atoms bonded; mixture: different substances not bonded

Difference between atoms and molecules

atom: single particle; molecule: two or more atoms bonded together

Pure substance vs mixture

pure substance: fixed composition; mixture: variable composition

Particle diagrams: determine formulae and atom ratios

count types of atoms shown

Common chemical symbols (list key ones)

H, He, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Fe, Cu, Zn

Write word equations for simple reactions

reactants → products (e.g., magnesium + oxygen → magnesium oxide)

Write formulae for common compounds (e.g., methane)

CH₄

Balance simple chemical equations (example)

2H₂ + O₂ → 2H₂O

Law of conservation of mass

mass is neither created nor destroyed in a chemical reaction

Why mass may appear to decrease in reactions involving gases

gas escapes into the air

Why mass may appear to increase in reactions involving gases

gas from air combines with reactants

Experimental setup for mass change investigation

use a balance; for gases use a sealed container or balloon to trap gas

Identify reactants and products in a reaction

reactants: starting substances; products: substances formed

What happens to particles during a chemical reaction?

atoms rearrange; chemical bonds break and new bonds form

DNA and chromosomes: what do they carry?

genes passed from parents to offspring determine inherited characteristics

Function of DNA

store and carry genetic information

Structure of DNA (shape)

double helix

DNA composition

sugar-phosphate backbone and nitrogenous bases

DNA shape description (alternate)

twisted ladder

Complementary base pairing

Adenine with Thymine (A-T); Cytosine with Guanine (C-G)

Variation definition

differences between individuals of the same species

Continuous variation definition

range of values (e.g., height)

Discontinuous variation definition

distinct categories (e.g., blood group)

Continuous variables are

measured and have many possible values

Discontinuous variables are

counted and have limited categories

Causes of variation

genetic factors (inherited genes) and environmental factors (e.g., diet, climate)

Species definition

group of organisms that can interbreed to produce fertile offspring

Closed circuit definition

complete circuit with no gaps or open switches, allowing current to flow

Bulb lights when

correctly connected to a battery in a closed circuit

Electric current definition

flow of electric charge (e.g., electrons)

Current unit

amperes (amps, A)

Series circuit: current rule

current is the same at all points

Ammeter connection

connected in series so current flows through it

Parallel circuit: current rule

total current into junction equals total current out; current splits between branches

Potential difference definition

measure of energy transferred per charge

Potential difference unit

volts (V)

Series circuit: potential difference rule

total p.d. shared between components; adds up to battery voltage

Parallel circuit: potential difference rule

p.d. across each branch is the same

Voltmeter connection

connected in parallel across a component

Series circuit: one component breaks

all components stop working

Parallel circuit: one component breaks

other components continue to work

Resistance definition

measure of how difficult it is for current to flow

Resistance formula

Resistance = Voltage / Current

Resistance unit

ohms (Ω)

Magnetic materials

iron, cobalt, nickel, steel

Magnetic field lines show

shape and direction of magnetic field

Where is magnetic field strongest?

at the poles (field lines closest together)

Magnetic field line direction

from north pole to south pole

Compass needle points in direction of

magnetic field

Earth has a magnetic field because

compass needles point towards geographic north

Mapping magnetic field with compass

plot needle direction at multiple points; join with smooth lines

Like poles

repel

Opposite poles

attract

Magnetic materials are

attracted to magnets

Non-magnetic materials are

not affected by magnets

Temporary magnets: domain behaviour

domains randomly arranged; easily aligned and randomised again

Current flowing through wire produces

magnetic field (shown by compass needle deflecting)

Electromagnet construction

wrap coil of wire around iron core; pass current through it

Electromagnet strength increased by

greater current and more turns of wire

Hydrocarbon definition

compound made only of carbon and hydrogen atoms chemically bonded

Hydrocarbon examples

methane CH₄, octane C₈H₁₈

Main source of hydrocarbons

crude oil (mixture of different hydrocarbons and small amounts of other substances)

Combustion definition

chemical reaction between a fuel (e.g., hydrocarbon) and oxygen

Complete combustion conditions and products

plentiful oxygen; produces carbon dioxide and water