Hypothesis : 

• Definition : A testable prediction about the outcome of an experiment.

• Example : More sunlight helps plants grow taller.

Variables : 

• Independent Variable : What you change.

  • Example : The amount of water you give to a plant.

• Dependent Variable : The variable that you measure in an experiment. It depends on the changes made to the independent variable.

  • Example : The height of a plant after a week of different amounts of sunlight.

• Controlled Variables : What stays the same.

  • Example : The type of plant, the amount of sunlight, and the soil used.

Data : 

• Quantitative Data : Uses numbers.

• Qualitative Data : Uses descriptions.

Graphs : 

• Line Graphs : Used for continuous data. (Two number based variables)

• Bar Graphs : Used for categorical data. 

Living Systems

The three principles that define a multicellular organism : 

• All living organisms are composed of one or more cells.

• A cell is the basic structural and functional unit of living organisms.

• All cells arise from pre-existing cells.

Cell Types : 

• Multicellular : Made up of more than one cell.

• Unicellular : Made up of one cell.

Levels of organization :

Body Systems : 

Skeletal System : 

• Main Organs : Bones, cartilage, ligaments, joints.

• Functions :

  • Support : Gives shape to the body.

  • Protection : Protects vital organs (e.g., rib cage protects the heart and lungs).

  • Movement : Works with muscles to allow movement.

  • Blood Cell Production : Bone marrow produces red and white blood cells.

Teeth  : 

• Incisors :

  • Found in the front (comprised of 4 teeth, two on the top, two on the bottom)

  • Used to bite into food and cut it into smaller pieces

• Molars :

  • Found mostly in the back

  • Used to grind up the smaller pieces of food into a size that can be transported through the oesophagus

• Canines :

  • Found in the front

  • Usually pointed

  • Used to tear into foods such as meats and vegetables

Digestive System : 

• Main Organs : Mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas.

• Functions :

  • Breakdown of Food : Digests food into smaller molecules.

  • Nutrient Absorption : Small intestine absorbs nutrients into the bloodstream.

  • Waste Elimination : Removes undigested food as waste.

Enzymes  : 

• Amylase :

  • Carbs -> sugar

  • Produced in salivary glands,pancreas, and small intestine.

• Protease :

  • Proteins -> Amino acids

  • Produced in stomach,pancreas and small intestine

• Lipase : 

  • Fats -> fatty acids

  • Produced in pancreas and small intestine

Circulatory System : 

Main Organs : 

• Heart : Located in the chest, slightly left of center. Pumps blood throughout the body.

• Blood Vessels : Include arteries, veins, and capillaries that transport blood.

• Blood : Carries oxygen, nutrients, and waste.

Functions : 

• Transport : Carries oxygen, nutrients, and hormones to cells.

• Waste Removal : Transports carbon dioxide and other waste products away from cells.

• Temperature Regulation : Helps regulate body temperature by distributing heat.

Blood Vessels : 

• Arteries : Have thick walls to withstand high pressure and carry oxygen-rich blood from the heart to the body.

• Veins : Collect oxygen-poor blood from the body and carry it back to the heart.

• Capillaries : Small blood vessels where nutrients, gases, and waste products are exchanged with cells.

Important Blood Vessels : 

• Pulmonary Artery : Carries oxygen-poor blood from the right ventricle of the heart to the lungs for oxygenation.

• Pulmonary Vein : Carries oxygen-rich blood from the lungs back to the left atrium of the heart.

• Aorta : The largest artery in the body; it carries oxygen-rich blood from the left ventricle to the rest of the body.

Heart Chambers : 

• Atriums (Left and Right): The upper chambers of the heart.

  • Right Atrium : Receives oxygen-poor blood from the body and sends it to the right ventricle.

  • Left Atrium : Receives oxygen-rich blood from the lungs and sends it to the left ventricle.

• Ventricles (Left and Right) : The lower chambers of the heart.

  • Right Ventricle : Pumps oxygen-poor blood to the lungs through the pulmonary artery.

  • Left Ventricle : Pumps oxygen-rich blood to the body through the aorta.

Heart : 

Definitions : 

Capillaries : 

Capillaries are thin and small blood vessels that are in your body. They transport blood, nutrients and oxygen to cells in your organs and body systems. Capillaries are the smallest blood vessels. The capillaries also take waste products away from your tissue

Excretory System : 

• Main Organs : Kidneys, bladder, ureters, urethra.

• Functions :

  • Waste Filtration : Kidneys filter waste and excess water from the blood.

  • Urine Production : Converts waste into urine.

  • Regulation : Helps maintain water and salt balance in the body.

Respiratory System

Main Organs : 

• Nose and Mouth: Air enters and is filtered.

• Trachea: Also known as the windpipe; transports air to the lungs.

• Bronchi: Two large tubes branching from the trachea into each lung.

• Lungs: Organs where gas exchange occurs.

• Alveoli: Tiny air sacs in the lungs where oxygen is absorbed into the blood and carbon dioxide is released.

• Diaphragm: Muscle beneath the lungs that helps in breathing by contracting and relaxing.

• Pharynx: Passageway for air, leads to the Trachea

• Bronchioles: A network of small branches leading from the bronchi into the lung tissue and ultimately the air sacs

Functions : 

• Gas Exchange: The main function is to exchange oxygen and carbon dioxide between the air and blood.

• Oxygen Intake: Oxygen from the air enters the bloodstream through the alveoli.

• Carbon Dioxide Removal: Carbon dioxide, a waste product, is expelled from the bloodstream through the alveoli and exhaled.

• Breathing Process: The diaphragm contracts to pull air into the lungs (inhalation) and relaxes to push air out (exhalation).

Definitions : 

Diaphragm : 

The diaphragm plays a critical role in the respiratory system, when you inhale, the diaphragm contracts and flattens, this creates a vacuum in your chest, allowing your chest to get bigger and pull in air.

Force & Motion : 

Force : 

• What is a Force? : A push or pull on an object.

  • Example : Kicking a ball applies force to move it.

What a Force Can Do :

• Effects of Force:

  • Change the speed of an object (faster or slower).

  • Change the direction of an object.

  • Change the shape of an object.

Measuring Forces :

• Equipment: Force is measured using a spring balance.

• Unit: Forces are measured in Newtons (N).

Friction :

• What is Friction? : A force that opposes the motion between two surfaces in contact.

  • Example : Rubbing your hands together creates heat due to friction.

Types of Friction Forces :

Types of Friction Forces:

1. Static Friction : Prevents objects from moving.

2. Sliding Friction : Opposes the motion of objects sliding over each other.

3. Fluid Friction : Resistance when an object moves through a fluid (air or water).

4. Air Resistance : A type of fluid friction that slows down objects moving through air.

5. Gravity : Acts downward, pulling objects toward the Earth.

6. Buoyancy : The upward force that allows objects to float in water or other fluids.

Relationship Between Weight and Mass :

Relationship Between Weight and Mass :

• Mass: The amount of matter in an object (measured in kilograms).

• Weight: The force of gravity acting on an object’s mass.

• Weight Equation : 

Weight-Mass-Gravity Triangle : 

W = Weight 

M = Mass

G = Gravity

Horizontal Line = Divide (÷), Vertical Line = Multiply (x)

How Gravity Works :

• Gravity : A non-contact force that pulls objects toward each other.

  • Earth’s Gravity : Pulls objects toward the center of the Earth, giving them weight.

Solving Problems on Gravity (w = m × g) :

• Example :

  • If an object has a mass of 5 kg, its weight would be : 

Electrostatic Forces :

• What is Electrostatic Force? : A force between objects with electric charges.

  • Example : Rubbing a balloon on your hair creates static electricity, making it stick to a wall.

Balanced and unbalanced forces :

• If forces are balanced : 

  • The object is moving at a constant speed OR is stationary.

• Forces are unbalanced if:

  • Unequal balance of forces in opposite directions

  • Change in motion and direction

Resultant Force : 

• Definition : The overall force when all individual forces acting on an object are combined.

• How it works :

  • Forces in the same direction: Add the forces together.

  • Forces in opposite directions: Subtract the smaller force from the larger one.

• Resultant Force = 0: The object stays at rest or keeps moving at a constant speed.

Example:

• Two people push a box with 5 N and 3 N in the same direction → Resultant force = 8 N.

• If one pushes with 6 N and the other pulls with 4 N in the opposite direction → Resultant force = 2 N in the direction of the larger force.

Atomic Structure :

• Structure of an Atom :

  • The atom consists of a central nucleus containing protons (positively charged) and neutrons (no charge).

  • Electrons (negatively charged) orbit around the nucleus in electron shells.

  • Valence Electrons :  are the electrons orbiting the nucleus in the farthest atomic shell

Charges:

• Fewer electrons than protons → Positive charge.

• More electrons than protons → Negative charge.

Atom Structure Image : 

4. Chemistry :

Elements : 

• Definition : Pure substances that cannot be chemically broken down.

• Characteristics :

  • Made of one type of atom.

  • Represented by chemical symbols (e.g., H for Hydrogen).

  • Listed in the Periodic Table.

Compounds : 

• Definition : Substances formed by the chemical combination of two or more elements.

• Characteristics :

  • Pure substances.

  • Cannot be separated by physical methods.

  • Elements lose their individual properties.

  • Composition is the same throughout.

  • Fixed melting point.

Chemical Change : 

• Definition : A process where substances change into new substances with different properties. Usually irreversible.

• Examples :

  • Rusting of iron.

  • Burning wood.

  • Cooking an egg.

  • Baking a cake.

  • Fireworks exploding.

A chemical change can be identifiable if

• The temperature of the mixture changes

• The acidity of the mixture changes

• Formation of gas

• Change in colour

• Formation of solids (precipitate)

• Chemical composition is altered

• Difficult to reverse

Physical Change : 

Definition : A physical change is a process where the substance changes, but the substance’s chemical composition is not altered by any means

These changes can be reversed for the most part.

End of notes.