Cells

Explain the need for cells to exchange substances with the environment, particularly in the process of respiration.

Cells: Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialised functions.

Cells → Respiration

• When we breathe, the respiratory system takes in oxygen and sends out carbon dioxide. The cells in our bodies need fresh oxygen to stay alive. As cells do their jobs, they make and give off carbon dioxide. This exchange of oxygen and carbon dioxide is called respiration.

Nutrients and The Digestive System

Explain the reasons living things require food in terms of energy, growth and repair. • Explain the requirements of aerobic respiration • Explain the process of aerobic respiration, including the chemical word equation. • Explain the process of digestion with reference to the function of the main organs involved. • Compare mechanical and chemical digestion • Describe structures in the digestive system that allow for absorption of nutrients. • Explain how the energy in food can be measured, when given a formula.

Nutrient: a substance that provides nourishment essential for the maintenance of life and for growth.

Digestive System: The digestive system is made up of the digestive tract and other organs that help the body break down and absorb food. It is a long, twisting tube that starts at the mouth and goes through the oesophagus, stomach, small intestine, large intestine and anus.

Why do living things require food?

• Living things require food in terms of energy, growth and repair as it a basic fundamental requirement for the sustainment of life. Within foods are nutrients, which are substances essential for growth, energy and repair; energy from these nutrients is needed to carry out basic life processes

Aerobic Respiration

• Requires oxygen (O2)

• During aerobic cellular respiration, glucose reacts with oxygen, forming ATP that can be used by the cell. Carbon dioxide and water are created as byproducts

  • ATP is an organic compound that our body uses for energy.

💡 Glucose + Oxygen ➡ Carbon Dioxide + Water + Energy

Process of Digestion

• Digestion is the breakdown of food into simple nutrients the body can absorb

• The digestive system breaks food down into proteins, fats and carbohydrates that are needed by the body

1. MOUTH: The entry point for food passing into the body; (teeth) biting and chewing help with physical digestion. The tongue works the food into a ball called a bolus, then pushes to the back of mouth to be swallowed. Saliva helps with chemical digestion. This is where the breakdown of most nutrients starts.

2. OESOPHAGUS: The tube that connects the throat to the stomach. Food is squeezed through the oesophagus by peristalsis, even if you're hanging upside down.

3. STOMACH: A muscular pouch that churns and squeezes food into liquid; churning and squeezing help with physical digestion. Gastric juices help with chemical digestion. Chyme is a semi-liquid mixture of partially digested food, stomach acid, and digestive enzymes that form in the stomach.

4. SMALL INTESTINE: A long, narrow tube where the body absorbs most nutrients, the small intestine has a large surface area to absorb nutrients into the bloodstream efficiently

5. LARGE INTESTINE: A wide tube where water is absorbed and most good bacteria live; good bacteria living in the large intestine help it break down fats and complex carbohydrates

6. ANUS: At the opening at the end of the digestive tract, solid waste is expelled by the body through the anus.

Mechanical vs Chemical Digestion

Mechanical Digestion

• Mechanical digestion involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion

• The breakdown of food by sources such as the mouth by churning, chewing, and biting

Chemical Digestion

• The breakdown of food by saliva enzymes saliva, stomach acid and other digestive juices

• Chemical digestion forms new substances, including simple nutrients that can be absorbed by the body, through the small intestine.

Absorption of Nutrients

• The movement of substances through tiny holes into the bloodstream. Water and nutrients are absorbed through tiny pores in the lining of the intestines.

• The small intestine absorbs most of the nutrients in your food, and your circulatory system passes them on to other parts of your body to store or use. Special cells help absorb nutrients cross the intestinal lining into your bloodstream

• Food is then squeezed into the lower parts of the small intestine, called the jejunum and the ileum. Nutrients are absorbed from the ileum, lined with millions of finger-like projections called villi. Each villus is connected to a mesh of capillaries. This is how nutrients pass into the bloodstream.

How can Energy be Measured?

• The equation for calculating the energy content of a food source via calorimetry is as follows:

💡  Energy (joules) = Mass of water (g) × 4.2 (J/gºC) × Temperature increase (ºC)

• Kilocalories

The Excretory System

Identify the structures of the human excretory system. •Describe the functions of the structures of the excretory system. •Describe the role of the excretory system in removing wastes and balancing salt and water in the blood.

Excretory System: The excretory system is a vital biological system that removes excess and waste products from the body to maintain homeostasis. Most of these products are in fact used and broken down components of metabolism that leave the body in the form of urine, sweat, or feces.

Function of the Structure

• Kidney: Filters all the impurities out of the blood and removes excess water from the body

  • Kidneys are in the abdomen, near the liver and stomach, and filter waste products from blood

• Ureter: Tubes that carries the urine from the kidney to the bladder

• Bladder: Holds urine until it builds up and is released

• Anus: Deposits feces

• Urethra: Deposits liquid wastes

  • The bladder receives urine from the kidneys via the ureters and excretes it via the urethra

Salt and Water in the Blood

• The urinary system removes waste from your blood in the form of urine

• Helps regulate blood volume and pressure, also regulates the levels of salt and chemicals within the body’s blood and cells.

  • Kidneys remove acid produced by the cells and maintains healthy levels of minerals.

Energy

Define energy and how can we detect it • Definition of energy as the ability to make things move and cause changes • Describe types of energy (make a list with examples) • Compare energy transfer and energy transformation

Energy: 1. the strength and vitality required for sustained physical or mental activity

            2.power derived from the utilisation of physical or chemical resources, especially to provide light and heat or to work machines

• We can detect energy from movement, sound, heat or light as they all are proofs that energy is present and being used

Energy’s Ability to Make Things Move and Change

• Energy is defined as the ability to do work

  • Which technically means that it can cause some kinds of change

• Energy that makes things move is “Kinetic Energy”

Types of Energy, Energy Transfer and Transformation

Types of Energy

• Kinetic Energy: Energy which a body possesses by virtue of being in motion

• Potential Energy: the energy that is stored in an object due to its position relative to some zero position

  • Gravitational Potential: energy an object possesses because of its position in a gravitational field

  • Elastic Potential: energy stored as a result of applying a force to deform an elastic object

  • Chemical Potential: the energy stored in the chemical bonds of a substance. The various chemicals that make up gasoline contain a large amount of chemical potential energy that is released when the gasoline is burned in a controlled way in the engine of the car

• Electrical Energy: the power an atom's charged particles have to cause an action or move an object

• Renewable Energy: energy from renewable resources that are naturally replenished on a human timescale

  • Renewable Solar: Energy created by the heat and light of the sun is called solar energy. Solar power is produced when energy from the sun is converted into electricity

  • Renewable Wind: Wind turbines harness energy from the wind using mechanical power to spin a generator and create electricity

• Thermal Energy: the energy contained within a system that is responsible for its temperature

Energy Transfer

• The conversion of one form of energy into another remaining in the same form

• A common example of energy moving between objects, called energy transfer, is the transfer of kinetic energy from a moving object to a motionless object. Kinetic energy is the energy of motion. When a bat hits a ball, some of the bat's kinetic energy moves to the ball. However, the energy stays in the same form

Energy Transformation

• The changing of forms of energy from one to another

• Gasoline (chemical) is put into our cars, and with the help of electrical energy from a battery, provides mechanical (kinetic) energy

Electrical Energy

Outline the essential elements of an electric circuit. • Compare conductors and insulators. • Identify symbols used in circuit diagrams. • Compare series circuit and parallel circuits. • Draw circuit diagrams to represent simple series circuit and parallel circuit.

Electrical Energy: Electrical energy is the power an atom's charged particles have to cause an action or move an object. The movement of electrons from one atom to another is what results in electrical energy.

Comparing conductors and insulators.

Conductors

• Electrons in conductors (metals) are free to move

  • Little to no resistance to the flow of electrons unlike insulators

  • In a conductor, the outer electrons of the atom are loosely bound and can freely move through the material when an electric charge is applied

• Metals, metal alloys, electrolytes, some non-metals such graphite or liquids, including water are good electrical conductors

Insulators

• Insulators do not allow electrons to flow through them

  • Electrons are tightly packed with atoms, not loosely bound like conductors

• Many objects made from non-metals are insulators

• Plastic and rubber are two very effective insulators

Electric Circuit Diagram Symbols

Comparing series circuits and parallel circuits

Series

• Connected in a one after the other manner

• Some currents flow through all the components in the circuit

• Different potential voltage exists across each component

• Single path

• Fault in one of the circuit components causes failure of the whole thing

• Less commonly used
  

Parallel

• Components are connected head to head manner

• Different current flows through each component in the circuit

• The potential voltage across the circuit is equal for the components

• Multiple paths

• Fault in a single component does not render the circuit unusable

• Commonly used in home lighting set ups.
  

Heat Energy

Explain differences between heat and temperature. • Describe heat energy and the three methods of heat transfer, with examples. • Explain convection currents – use models to visualise them. • Describe radiation – for example infra-red and how this is related to the Sun.

Heat Energy: The term "thermal energy" is used loosely in various contexts in physics and engineering, generally related to the kinetic energy of vibrating and colliding atoms in a substance.

The 3 Methods of Heat Transfer

Conduction

• Solids are usually very good conductors of heat because the particles in them are packed closely together

• Gases are the poorest conductors because the particles that they are made of are far apart

• Metals are generally good conductors of heat and electricity

• Different metals conduct heat to different extents

• Non-metals, such as glass, plastics and wood do not conduct as well

• Materials that conduct heat and electricity poorly are insulators

Convection

• The spread of heat due to the movement of particles in liquids and gases is called convection

• Heat travels through liquids and gases by convection

• Heat rises, Cold sinks

Radiation

• Heat transfer that moves in waves, does not rely on movement of particles

• It does not require particles to transfer heat from one place to another

• Heat that travels by radiation is called radiation heat

• Radiant heat can be reflected, transmitted, or absorbed

  • Reflection = bounce off/sent back

  • Transmitted = pass through/broadcast

  • Absorbed = heat is taken in and temperatures of the surface rise

Convection Currents

• When a liquid or gas is heated, the particles in the heated region become more spread out, or less dense. Liquid or gas that is less dense than the rest of the substances will rise, taking heat with it. This flow of warm air up and cool air down creates a circular current called convection currents.

• Convection currents are the results of differential heating. Less dense (lighter), warm material rises while more dense (heavier) cool material sinks. This is the movement that creates the circular pattern that we see all throughout our world.

Radiation

• Radiation is the emission of energy in the form of waves or particles.

• In the context of the Sun, it includes various forms of electromagnetic radiation.

• Infrared radiation is a type of electromagnetic radiation with longer wavelengths than visible light, we can only feel it in the form of heat.

• The Sun emits infrared radiation along with other types of electromagnetic radiation.

• Infrared radiation from the Sun is responsible for heating the Earth and plays a key role in the Earth's greenhouse effect.