Edexcel iGCSE Biology

Processes of living organisms

Movement, reproduction, sensitivity, control, growth, respiration, excretion, nutrition

Types of living organisms

Animal, Plant, Bacteria, Protoctist, Fungi, Virus

Structure of Animal Cells

Cell Membrane, Cytoplasm, Nucleus

Characteristics of Animals

Multicellular, feed on other organisms, carbohydrates as glycogen

Example of Animals

Human or Mosquitos

Invertabrates

Animals which lack a backbone. E.g. Worms

Vertabrates

Animals with a backbone. E.g. Humans

Structure of Plant Cells

Cellulose cell wall, Cell membrane, Cytoplasm, Chloroplasts, Sap Vacuole, Nucleus

Characteristics of Plants

Multicellular, contain chloroplasts to carry out photosynthesis, cellulose cell walls, carbohydrates as starch or sucrose

Example of Plants

Flowering plants: maize, herbaceous legumes: peas

Structure of Fungi

Chitin cell wall, cell membrane, cytoplasm, vacuole, nucleus

Characteristics of Fungi

Multicellular or unicellular, hyphae structures, no photosynthesis, nutrition by secreting digestive enzymes on dead organisms, carbohydrates as glycogen

Example of Fungi

Multicellular: Mushrooms, Unicellular: Yeast

Characteristics of Protoctists

Microscopic, usually unicellular, can resemble plants or animals

Example of Protoctists

Amoeba, Chlorella

Structure of Bacteria

Cell wall, cell membrane, capsule, plasmids, nucleoid chromosome, sphere, rod, or spiral shape

Characteristics of Bacteria

Unicellular, small organisms, circular DNA instead of nucleus, some can photosynthesis others are saprotrophic feeding

Example of Bacteria

Lactobacillus bulgaricus, Pneumoccus

Structure of Virus

Membrane from host cell, protein coat, DNA or RNA

Characteristics of Virus

Smallest organisms, non cellular, parasitic pathogens

Example of Viruses

Influenza, HIV

Pathogens

Organisms which cause disease, usually fungi or bacteria

Levels of organisation

Organ systems, Organs, tissues, cells, organelles

Organ systems

A group of organs that work together to perform a particular function

The organ systems

Digestive, respiratory, circulatory, excretory, nervous, hormonal, reproductive

Organs in the Digestive system

Oesophagus, stomach, intestines

Function of the Digestive system

Digest and absorb food

Organs in the Respiratory system

Lungs and trachea

Function of the Respiratory system

Gas exchange

Organs in the Circulatory system

Heart and bloods vessels

Function of the Circulatory system

Carry oxygen and food around the body

Organs in the Excretory system

kidney's, bladder, liver

Function of the Excretory system

Remove wastes and toxins

Organs in the Nervous system

Brain, spinal cord, nerves

Function of the Nervous system

Send messages and responses around the body

Function of Skeletal and Muscle systems

Movement, support and protection

Organs in the reproductive system

Ovaries and Testes

Function of reproductive system

Produce an offspring

Tissues

Cells with a similar function that are grouped together

Organs

A group of tissues acting together to perform a particular function

Cells

Structural units of organisms

Organelles

Structures inside cells like cytoplasm and cell membranes

Nucleus

Largest organelle containing chromosomes which carry genetic material

Cell Membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

Cytoplasm

a jellylike fluid inside the cell where the organelles are found

Cell wall

Layer of freely permeable material, cellulose or chitin, outside the cell membrane that keeps the cell's shape

Chloroplasts

Absorb light energy to make food in the process of photosynthesis; green due to presence of chlorophyll

Vacuole

Filled with cell sap, a store of dissolved sugars, mineral ions and other solutes. Permanent in plants

Function of Nucleus

To control the activities of the cell and hold the genetic material

Function of Cell membrane

Controls what enters and leaves the cell

Function of Cytoplasm

Where chemical reactions take place

Function of Cell Wall

Provide the cell with support and protection

Function of Vacuole

Store molecules like amino acids and sugars

Function of Chloroplasts

Where photosynthesis occurs

Chemical elements in carbohydrates

Carbon, hydrogen, and oxygen

Chemical elements in proteins

Carbon, hydrogen, oxygen, and nitrogen

Chemical elements in lipids

Carbon, hydrogen, and oxygen

Simple molecules of carbohydrates

Starch and glycogen made up of simple sugars

Simple molecules of protein

Long chains of amino acids

Simple molecules of lipids

Chains of glycerol and fatty acids joined together

Test for glucose

Add Benedict solution to a solution of dissolved glucose. Heat to observe color change blue to orange

Test for starch

Iodine solution goes brown to blue-black

How do enzymes work as biological catalysts

Reaction occurs faster and under moderate conditions. Turns substrate into product through lock and key, enzyme remains unchanged and can repeat

Enzymes as biological catalysts

Enzymes provide a route with lower activation energy to turn substrates into products without extreme heat or ph that could damage cells

Temperature effect on enzymes

Extremely high or low temperatures can denature enzymes

pH effect on enzymes

Acidic or Alkali conditions change the shape of the active site which slows the reaction. Optimum pH depends on the enzyme

Diffusion

The movements of particles down a concentration gradient from an area of high concentration to low until concentration is uniform

Osmosis

The movement of water across a semi permeable membrane down a concentration gradient from dilute to concentrated

Active transport

Movement of molecules from an area of low concentration to high concentration with an energy requirement

Factors that affect rate of movement of substances in and out of cells

Surface area to volume ratio, temperature and concentration gradient.

How surface area to volume ratio affects rate of movement

Increase surface area with same volume increase rate of movement

How temperature affects rate of movement

Temperature is average kinetic energy so a high temperature increases kinetic energy therefor increased rate

How concentration gradients affects rate of movement

A high concentration gradient increases rate of diffusion into cells

Photosynthesis equation

6CO₂+6H₂O→C₆H₁₂O₆+6O₂

Photosynthesis

The process of converting light energy into chemical energy

Factors affecting the rate of photosythesis

Concentration of carbon dioxide, light intensity, temperature

How carbon dioxide affects the rate of photosythesis

Increasing carbon dioxide levels through hydrocarbonate solution will increase the rate until constant

How light intensity affects the rate of photosythesis

More light, through a lamp or direct sunlight, increases the light energy to the chloroplast until constant

How temperature affects the rate of photosynthesis

Enzymes in the process of photosynthesis work at an optimum temperature

Leaf adaptations for photosynthesis

Large surface area to collect, thin for diffusion, palisade cells in upper section, chloroplasts containing chlorophyll, stomatal pores allowed in, space in mesophyll for diffusion of CO₂ and movement of water, xylem transports water, phloem translocates sugars.

Why do plants need mineral ions

For growth, magnesium ions for chlorophyll and nitrate ions for animo acids

Carbohydrates in the diet

Starches and sugars for energy stores

Balanced diet

correct proportions of the food groups

Why do humans need food

energy to respire and matter for cells and tissues

Water in the diet

needed in the semi liquid cytoplasms to allow movement of particles and allow chemical reactions to occur

Fats in the diet

Long term energy stores and insulation layer

Proteins in the diet

growth and repair of muscle tissues, make up hair, muscles and enzymes

Fibre in the diet

Allows for peristalsis, aids digestive system and increases roughage

Sources of carbohydrates

Bread, Pasta

Sources of proteins

Fish, meat, leafy vegetables

Sources of lipids

Dairy, nuts

Vitamin A in the diet

Creates visual pigment in retina and prevents night blindness

Sources of Vitamin A

Carrots, meat, fish

Vitamin C in the diet

Makes connective tissue to heal wounds and prevent scurvy

Scurvy

A disease caused by a lack of vitamin C. Symptoms of gums bleeding, wounds not healing and loose internal organs

Vitamin D in the diet

promotes calcium absorption, prevents rickets and oestoperosis

Sources of Vitamin C

Citrus fruits

Sources of Vitamin D

sunlight, fatty fish

Calcium in the diet

Normal growth and maintains teeth and bones.

Osteoporosis

Deficiency in calcium leading to bones weakening and thinning