B1 SCIENCE IGCSE

Organism

A living thing

Cells

Smallest units from an organisms

LEVELS OF ORGANIZATION WITHIN LIVING ORGANISMS

cells → tissues → organ → system → organ system → organisms

Cell Wall

(plant cell only)

made of cellulose

criss-cross fibres of cellulose support / keep it shape + strong

fully permeable can gas through

keep the structure of the cell

Cell membrane

thin layer of protein & fat

selective / partially permeable (not all can go through)

can control movement of some substance go in/out of the cell

👉 control what goes in and out + stop invader → cell safe.

Cytoplasm

clear jelly, 70% water

substance dissolve in it (especially proteins)

structure in the cytoplasm called organelles

👉 where MANY metabolic reactions happen.

Vacuole

(plant cell only)

have a membrane to hold it liquid

store sugar, ion that are important

vesicle

a very small vacuole

Chloroplasts

(plant cell only)

in most green part of the plant (especially leaves contain chloroplast)

absorb light energy for photosynthesis.

Ribosomes:

Produce protein from amino acid during protein synthesis or translation.

Mitochondria:

power house of the cell

they have their own DNA (circle shape)

produce energy

generate most chemical energy needed through respiration

aerobic respiration

chemical reactions that take place in mitochondria, which use oxygen to break down glucose and other nutrient molecules to release energy for the cell to use.

fully permeable

allow small molecules and ions to pass through it.

metabolic reaction

chemical reactions that take place in living organism

Eukaryotes

animal, fungi, plants, protist

Prokaryotes

bacteria

Eu in Eukaryotes means

new

Pro in Prokaryotes means

prototype

bacteria

unicellular organisms whose cells do not contain a nucleus.

prokaryotic cells:

cells with no nucleus; bacteria have prokaryotic cells.

plasmids:

small, circular molecules of DNA, found in many prokaryotic cells in addition to the main, much larger circle of DNA.

Tissue

A group of similar cells that work together to perform a function.

Epidermis

The outer protective layer of plants (and also skin in animals).

Root hair cell

Plant cell near root tips that absorbs water and minerals.

Palisade mesophyll cell

Plant leaf cell that carries out photosynthesis.

Red blood cell

Animal cell that transports oxygen in the blood.

Ciliated cell

Animal cell with tiny hairs (cilia) that sweep mucus out of the airways.

Neurone

Nerve cell that carries electrical messages through the body.

Sperm cell

Male reproductive cell (gamete) that carries DNA to fertilise the egg.

Egg cell

Female reproductive cell (gamete) containing DNA and nutrients for a new organism.

organ:

a structure made up of a group of tissues, working together to perform specific functions.

digestion:

the breakdown of food.

organ system:

a group of organs with related functions, working together to perform body functions.

magnification:

how many times larger an image is than an object. (I = AM)