igcse bio ch 1, 2

movement

movement is an action by an organism or part of an organism causing a change of position or place.

respiration

Respiration as the chemical reactions in cells that break down nutrient molecules and release energy for metabolism.

sensitivity

Sensitivity as the ability to detect and respond to changes in the internal or external environment.

growth

Growth as a permanent increase in size and dry mass.

reproduction

Reproduction as the processes that make more of the same kind of organism.

Excretion

Excretion as the removal of the waste products of metabolism and substances in excess of requirements.

Nutrition

Nutrition as the taking in of materials for energy, growth and development.

classification of organisms

Organisms can be classified into groups by the features that they share

species

A species is a group of organisms that can reproduce to produce fertile offspring.

binomial system

The binomial system of naming species is made up of two parts showing the genus and species.

genus

name of the genus starts with the capital letter

species

name of species starts with a lowercase letter

dichtonomous keys

all we need to do is group species in terms of their features and answer

use of dna sequencing in classification

• each species has a unique sequence of bases in its DNA

• this makes it distinguishable from other species

• if genetic differences are found, organisms will be classified as separate species

• base sequences of DNA if are similar, they are closely related

Sequence of classification

The sequence of classification is: Kingdom, Phylum, Class, Order, Family, Genus, Species

Animal cell features

• They are multicellular

• Their cells contain a nucleus but no cell walls or chloroplasts

• They feed on organic substances made by other living things

Plant cell features

• They are multicellular

• Their cells contain a nucleus, chloroplasts and cellulose cell walls

• They all feed by photosynthesis

Fungi Features

• usually multicellular

• cells have nuclei and cell walls not made from cellulose

• do not photosynthesize but feed by saprophytic (on dead or decaying material) or parasitic (on live material) nutrition

Protoctists Features

• Most are unicellular but some are multicellular

• All have a nucleus, some may have cell walls and chloroplasts

• This means that some protoctists photosynthesise and some feed on organic substances made by other living things

Prokaryotes Features

• They are often unicellular

• Their cells have cell walls (not made of cellulose) and cytoplasm but no nucleus or mitochondria

Mammals

• FUR/HAIR ON SKIN

• HAVE A PLACENTA

• YOUNG FEED ON MILK FROM MAMMARY GLANDS

• EXTERNAL EARS (PINNA) VISIBLE

• ENDOTHERMIC
  E.g:- Horse, Dog, Squirrel, Human

Birds

• SKIN COVERED IN FEATHERS

• HAVE 2 LEGS AND 2 WINGS INSTEAD OF FORELIMBS

• LAY EGGS WITH HARD SHELLS ON LAND

• HAVE A BEAK

• ENDOTHERMIC
  E.g:- Parrot, Blue Tit, Eagle

Reptiles

• DRY, FIXED SCALES ON SKIN

• LAY EGGS WITH RUBBERY SHELLS ON LAND
  E.g:- Snake, Turtle, Iguana

Amphibians

• SMOOTH, MOIST SKIN

• ADULTS USUALLY LIVE ON LAND (SO HAVE LUNGS), LARVAE LIVE IN WATER (SO HAVE GILLS)

• LAY EGGS WITHOUT SHELLS IN WATER
  E.g:- Frog, Toad, Newt

Fish

• LOOSE, WET SCALES ON SKIN

• GILLS TO BREATHE

• LAY EGGS WITHOUT SHELLS IN WATER
  E.g:- Flounder, Grouper

Myriapods

• BODY CONSISTS OF MANY SEGMENTS

• EACH SEGMENT CONTAINS AT LEAST 1 PAIR OF JOINTED LEGS

• 1 PAIR OF ANTENNAE
  E.g:- Centipede

Insects

• 3 PART BODY

• HEAD, THORAX AND ABDOMEN

• 3 PAIRS OF JOINTED LEGS

• 2 PAIRS OF WINGS (1 OR BOTH PAIRS MAY BE VESTIGIAL

• MEANING NON-FUNCTIONAL AND UNDEVELOPED)

• 1 PAIR OF ANTENNAE
  E.g:- Butterfly

Arachnids

• 2 PART BODY

• CEPHALOTHORAX AND ABDOMEN

• 4 PAIRS OF JOINTED LEGS

• NO ANTENNAE
  E.g:- Spider

Crustaceans

• MORE THAN 4 PAIRS OF JOINTED LEGS

• CHALKY EXOSKELETON FORMED FROM CALCIUM

• BREATHE THROUGH GILLS

• 2 PAIRS OF ANTENNAE
  E.g:- Crab

Why plants are green

At least some parts of any plant are green, caused by the presence of the pigment chlorophyll which absorbs energy from sunlight for the process of photosynthesis

Ferns

• Have leaves called fronds

• Do not produce flowers but instead reproduce by spores produced on the underside of fronds

Flowering Plants

• Reproduce sexually by means of flowers and seeds

• Seeds are produced inside the ovary found at the base of the flower

• Can be divided into two groups – monocotyledons and dicotyledons

Monocotyledons

• Flowers from monocotyledons contain petals in multiples of 3
• Leaves from monocotyledons have parallel leaf veins

Dicotyledons

• Flowers from dicotyledons contain petals in multiples of 4 or 5

• Leaves from dicotyledons have reticulated leaf veins (meaning that they are all interconnected and form a web like network throughout the leaf)

Virus

• Viruses are not part of any classification system as they are not considered living things

• They do not carry out the seven life processes for themselves, instead they take over a host cell’s metabolic pathways in order to make multiple copies of themselves

• Virus structure is simply genetic material (RNA or DNA) inside a protein coat

Nucleus

• CONTAINS GENETIC MATERIAL IN CHROMOSOMES WHICH CONTROL HOW CELLS GROW AND WORK

• CONTROLS CELL DIVISION

Cytoplasm

• SUPPORTS CELL STRUCTURES

• SITE OF MANY CHEMICAL REACTIONS

• CONTAINS WATER AND MANY SOLUTES

have a break of 5 minutes :)

if dont want a break, you can proceed

Cell Membrane

• HOLDS THE CELL TOGETHER

• CONTROLS SUBSTANCES ENTERING AND LEAVING THE CELL

Cell Wall

GIVES THE CELL EXTRA SUPPORT AND DEFINES ITS SHAPE

Chloroplasts

• SITE OF PHOTOSYNTHESIS, PROVIDING FOOD FOR PLANTS

• THE CHLOROPHYLL PIGMENTS ABSORB LIGHT ENERGY NEEDED FOR THE REACTION TO OCCUR
  

Vacuole

• CONTAINS CELL SAP

• USED FOR STORAGE OF CERTAIN MATERIALS

• ALSO HELPS SUPPORT THE SHAPE OF THE CELL

Mitochondria

• SITE OF AEROBIC RESPIRATION, PROVIDING ENERGY FOR THE CELL

• CELLS WITH HIGH RATES OF METABOLISM (CARRYING OUT MANY DIFFERENT CELL REACTIONS) WILL HAVE SIGNIFICANTLY HIGHER NUMBERS OF MITOCHONDRIA THAN CELLS WITH LOWER NUMBERS OF REACTIONS TAKING PLACE IN THEM

Ribosomes

SITE OF PROTEIN PRODUCTION IN PROTEIN SYNTHESIS

Vesicles

USED TO SAFELY TRANSPORT SUBSTANCES FROM ONE PART OF THE CELL TO ANOTHER

Specialized Cells

Specialised cells are those which have developed certain characteristics in order to perform particular functions

Differentiation

a process by which cells develop the structure and characteristics needed to be able to carry out their functions

Function of Ciliated Cell

movement of mucus in the trachea and bronchi

Function of Root hair cells

absorption

Function of Palisade Mesophyll cell

photosynthesis

Function of Neurones

Conduction of electrical impulses

Function of Red blood cells

transport of oxygen

Function of sex cells

Reproduction

Cells

BASIC FUNCTIONAL AND STRUCTURAL UNITS IN A LIVING ORGANISM

Tissues

GROUPS OF CELLS OF SIMILAR STRUCTURE WORKING TOGETHER TO PERFORM THE SAME FUNCTION

Organs

MADE FROM DIFFERENT TISSUES WORKING TOGETHER TO PERFORM SPECIFIC FUNCTIONS

Organ Systems

GROUPS OF ORGANS WITH RELATED FUNCTIONS, WORKING TOGETHER TO PERFORM BODY FUNCTIONS

Magnification

MAGNIFICATION = IMAGE SIZE / ACTUAL SIZE

1mm = how many micrometers?

1mm = 1000μm