IGCSE BIOLOGY 0610

2023, 2024, and 2025 syllabus DOESNT INCLUDE PRACTICALS

Organism

A living thing that carries out the seven life processes (MRS GREN).

MRS GREN

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition

Movement

An action by an organism that changes its position.

Respiration

A chemical reaction in cells which breaks down molecules to release energy for metabolism.

Sensitivity

An organism sensing what's happening around them and being able to respond to the changes (either internal or external).

Growth

An irreversible increase of an organism's size over a given period of time.

Reproduction

The biological process of producing offspring similar to itself.

Excretion

Process by which metabolic wastes are eliminated from the body and other excess substances.

Nutrition

The taking in of food and converting it into energy necessary for health, development and growth.

Why do we classify organisms?

- To easily identify and distinguish them.

- To easily discover their origins.

- To classify/ identify new organisms based on features they exhibit.

How are organisms classified?

Organisms are classified into groups by the features they share.

What is the aim of classification systems?

To reflect on evolutionary relationships.

What are the levels of classification?

1. Kingdom

2. Phylum

3. Class

4. Order

5. Family

6. Genus

7. Species

Kingdom

First and largest category used to classify organisms (divded into 5 kingdoms)

Species

A group of organisms with similar features and interbreed with each other to reproduce fertile offsprings.

Binomial nomenclature/ Binomial system of naming of species

An internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and then the species. i.e homo (genus) sapiens (species).

What do classification systems aim to reflect?

Evolutionary relationships.

What are the sequences of bases in DNA are used as?

A means of classification.

Similar base sequences in DNA are found in: distant ancestors or organisms with a more recent ancestor?

Groups of organisms which share a more recent ancestor (are more closely related) have base sequences in DNA that are more similar than those that share only a distant ancestor.

5 Kingdoms of life

Animal, Plant, Fungus, Prokaryote, Protoctist

Features of Animals

- Multicellular

- Ingestive (eating and drinking)

- Heterotrophs (obtains nutrition from other organisms)

Features of Plants

- Multicellular

- Photosynthetic

- Autotrophs (make their own food)

Features of Fungi

- Uni/Multicellular

- Mycelium and hyphae

- Reproduce through spores

- Saprotrophs (feed off of decaying organic material)

Features of Prokaryotes

- Unicellular

- No nucleus or cytoplasm

- Plasmids

Features of Protoctists

- Unicellular

- Nuclear

Vertebrates

- Animals with a backbone.

- Mammals, Birds, Reptiles, Amphibians, Fish.

Features of Mammals

- Fur/hair on skin

- Internal fertilization

- Births young

- Feed on mom's milk through mammary glands.

Features of Birds

- Feathers on body, scales on legs.

- Internal fertilization

- Hard eggs

- Strong, light bones.

Features of Reptiles

- Thick, dry, scaly skin.

- Internal fertilization

- Soft eggs

- 4 legs

Features of Amphibians

- Smooth, moist skin

- External fertilization

- Soft eggs

- Live on land and water.

Features of Fish

- Wet scales

- External fertilization

- Soft eggs

- Breathe through operculum and gills.

Invertebrates: Arthropods

- Animals without a backbone.

- Myriapods, Insects, Arachnids, Crustaceans.

Features of Myriapods

- 1 pair of antennae

- Many body segments

- 10+ pairs of legs

eg. centipede

Features of Insects

- 1 pair of antennae

- 3 body segments

- 3 pairs of legs

- 1/2 pairs of wings

eg. fly

Features of Arachnids

- 2 body segments

- 4 pairs of legs

eg. spider

Features of Crustaceans

- 2 pairs of antennae

- 3 body segments

- 4+ pairs of legs

- 1 pair of compound eyes

eg. crab

Features of Ferns

- No flowers or seeds

- Reproduce through spores

Flowering Plants

- Seeds in flower ovary

- Reproduce sexually

eg. dicots and monocots

Features of Monocotyledons

- One cotyledon (store food for the growing embryo).

- Parallel veins

- Long, narrow leaves

- 3 flower parts

- Scattered vascular bundle

Features of Dicotyledons

- Two cotyledons (store food for the growing embryo).

- Branched veins

- Broad leaves

- 4 or 5 flower parts

- Ringed vascular bundle

Features of Viruses

- Not considered living things because they don't reproduce on their own, can't complete metabolic actions and don't have cells.

- Reproduce by taking over the host cell's metabollic pathways to copy themselves.

- Structure contains of genetic material surrounded by protein coat.

Cell

The basic unit of structure and function in living things.

Tissue

A group of similar cells that perform the same function.

Organ

Group of tissues that work together to perform closely related functions.

Organ system

Group of organs that work together in performing same body functions.

Structure of bacterial cell

Cell wall, cell membrane, cytoplasm, ribosome, circular DNA, plasmids

Cell structure

Cell wall, cell membrane, nucleus, cytoplasm, chloroplast, ribosome, mitochondria, vacuole

Function of cell wall

- Tough layer, made of cellulose, surrounding the cell membrane.

- Protects and keeps the cell rigid to help define its shape.

Function of cell membrane

- Thin layer, made of proteins and fat, surrounding every cell and controls what enters and exits the cell.

- Partially permeable.

Function of nucleus

Controls all the cells activities and contains the cells DNA

Function of cytoplasm

Clear, jelly- like substance where metabolic reactions take place.

Function of chloroplast

Contains chlorophyll and absorbs light for photosynthesis.

Function of ribosome

Tiny structures where protein synthesis takes place.

Function of mitochondria

Small structure where aerobic respiration takes place.

Function of vacuole

Space filled fluid (in plants, cell sap) surrounded by its own membrane which store certain materials.

Specialized cells

Have certain characteristics in order to perform particular functions.

Ciliated cell

Function: movement of mucus in the trachea and bronchi.

Adaptation: small hair-like structures, cilia.

Root hair cell

Function: absorption.

Adaptation: thin cell walls, large surface.

Palisade mesophyll cell

Function: photosynthesis.

Adaptation: chloroplasts, column shaped.

Neurones

Function: conduct electrical impulses.

Adaptation: long, nerve endings on both sides.

Red blood cell

Function: transport of oxygen.

Adaptation: biconcave for large surface area, no nuclear, hemoglobin.

Sperm cell

Function: reproduction.

Adaptation: flagellum to help swim, packed with mitochondria, enzymes in the acrosome.

Egg cell

Function: reproduction.

Adaptation: lots of cytoplasm to store nutrients, cell membrane/jelly coat changes after one sperm enters.

Magnification

Image size/Actual size

1mm to μm

1000μm

Diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient as a result of their random movement.

Energy for diffusion comes from...

The kinetic energy of the random movement of ions and molecules, known as brownian motion.

Importance of diffusion of gases and solutes

- Get rid of waste products.

- Carry out gas exchange for respiration.

- Obtain nutrients for growth.

Factors affecting diffusion

- Surface area

- Concentration

- Distance

- Temperature

Role of water as a solvent

- Digested food molecules in the alimentary canal need to be moved to cells.

- Toxic substances (eg. urea) and substance in excess of requirements (eg. salts) can be easily dissolved in water to be excreted.

- Dissolved substances can be transported around the organism (eg. xylem/phloem of plants and dissolved food in blood).

Osmosis

The net movement of water from a region of high water potential (concentrated solution) to a region of lower water potential (dilute solution), through a partially permeable membrane.

Effects on plant cells when placed in solutions with different concentrations

Importance of water potential and osmosis in the uptake and loss of water

Effects on animal cells when placed in solutions with different concentrations

Active transport

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration

Importance of active transport

Process for movement of molecules or ions across membranes, including ion uptake by root hairs

Elements that make up carbohydrates

Carbon, hydrogen, oxygen

Elements that make up fats

Carbon, hydrogen, oxygen

Elements that make up proteins

Carbon, hydrogen, oxygen, nitrogen

Starch, glycogen and cellulose are made from

Glucose

Proteins are made from

Amino acids

Fats and oils are made from

Fatty acids and glycerol

Test for starch

Iodine solution

Test for reducing sugars

Benedict's test

Test for proteins

Biuret test

Test for fats and oils

Ethanol emulsion test

Test for vitamin C

DCPIP

Structure of DNA molecule

- Two strands coiled together to form a double helix

- Each strand contains chemicals called bases

- Bonds between pairs of bases hold the strands together

- The bases always pair up in the same way: A with T and C with G

Catalysts

Substance that increases the rate of a chemical reaction and is not changed by the reaction

Enzyme

Proteins that are involved in all metabolic reactions, where they function as biological catalysts

Importance of enzymes

Maintain reaction speeds of metabolic reactions.

Enzyme action

Effect of temperature on enzymes

Effect of pH on enzymes

Photosynthesis

Process by which plants synthesise carbohydrates from raw materials using energy from light

Word equation for photosynthesis

Carbon dioxide + water -> glucose + oxygen

in the presence of light and chlorophyll

Chemical equation for photosynthesis

6CO2 + 6H2O -> C6H12O6 + 6O2

Chlorophyll

Green pigment that is found in chloroplasts

Plants use carbohydrates for and in the form of

- Starch as an energy store

- Cellulose to build cell walls

- Glucose used in respiration to provide energy

- Sucrose for transport in the phloem

- Nectar to attract insects for pollination