Biology unit 2

Osmosis

Osmosis

The diffusion of water from a dilute solution to a concentrated solution across a semi permeable membrane

Turgid

When a cell is full, its contents push against the cell wall

plasmolyzed

When cells lose water and the cell membrane pulls away from the cell wall

cell membranes

Allow some substances to pass through as they are selectively permeable

How materials move in and out of cells

Diffusion, active transport, osmosis

Transpiration

The loss of water via evaporation, water diffuses out of the stomata

Functions of water in plants

Water for transpiration, photosynthesis, transport of minerals, cell support

Conditions that affect rate of transpiration

Humidity, temperature, wind conditions

Role of cell wall

Restricts water intake to prevent cell bursting

Genes

Short lengths of DNA which code for a particular characteristic or protein

Shape of DNA

Double helix

A links with

T

C links with

G

Complementary base pairing

The arrangement of bases along the length of DNA determines how a gene works

nucloetide

A building block of DNA consisting of a phosphate, sugar and a base

Genetic code

Bases along one side of the DNA molecule- the coding strand

base triplet

The sequence of bases that codes for an amino acid

Erwin Chargaff

Found that there was equal amounts of AT and GC

Franklin and Wilkins

Used X Ray diffraction to find the 3D shape of DNA

Watson and Crick

Built a 3D model of the model of DNA and discovered the double helix shape

Clone

A genetically identical cell

Mitosis

Allows cells to grow and replaces warn out cells and repairs damaged tissue

In mitosis a parent cell divides to form

2 genetically identical daughter cells

Chromotids

The original chromosome and the copy of it

Gregor Mendel

Father of genetics

Monohybrid case

Only one factor is considered

Alleles

Alternative forms of the same gene

homozygous dominant

AA

homozygous recessive

aa

Heterozygous

Aa

Fertilisation

When the sperm and egg fuse in the oviduct

Use of amniotic fluid

Cushions and protects embryo

What is passed through umbilical cord

Glucose, oxygen

How the placenta is adapted

Villi provide a large surface area for diffusion, good blood supply ensuring diffusion gradient, short distance between mothers blood and baby's blood

Superovulation

Multiple eggs are released

Mutation

Random change to the structure or number of chromosomes

Genetic screening

Involves testing for the presence of a particular genetic condition or allele

genetic engineering

Changing the DNA of living organisms, commonly bacteria as it is easily manipulated and multiplies easily

Biodiversity

Variety of living organisms

Variation

Any difference between individuals of the same species

Types of Variation

Continuous, discontinuous

Continuous variation

Where there is a gradual transition e.g. Heights

Charles Darwin

discovered natural selection

Three main components of the circulatory system

Blood, blood vessels, heart

Main function of circulatory system

Transport various substances e.g. Oxygen, glucose, vitamins. Protection from disease

Red blood cells

Carry oxygen around the body, large surface area, contains haemoglobin, no nucleus

white blood cells

Protect the body from disease

Phagocytes

Engulf and digest micro organisms ( phagocytosis)

Lymphocytes

Produce antibodies which clump together micro organisms therefore they cannot reproduce and spread, also are made visible in the blood to phagocytes

Function of hepatic portal vein

Carries blood from the digestive system to the liver

Function of coronary arteries

Brings oxygen to the heart

double circulation

When blood goes through the heart twice in one complete circuit

Louis Pasteur

Disproved spontaneous generation through swan neck flask experiment

Steralization

Raise temp very high to kill all bacteria

Pasteurization

Raise temp so most bacteria will be killed

Pathogen

An organism that causes disease

Types of pathogens

Bacteria, Viruses, Fungi

Renal artery

Contains urea, has oxygen and glucose

Renal vein

No urea, no oxygen but has glucose and co2

Hepatic artery

Has toxic waste products and oxygen and glucose

Hepatic vein

No toxins

Bodies defences / barriers

Nose, skin, eyes, blood, stomach

Antigens

Chemicals on the surfaces of pathogens, which cause lymphocytes to react

Lymphocytes produce

Antibodies and phagocytes

Vaccinations

Liquid containing dead or modified pathogens which are administered to the body, they contain antigens which stimulate an immune response

Edward Jenner

Discovered the small pox vaccine.

Antibiotics

Chemicals such as penicillin which are used against bacterial diseases to kill them or reduce their growth

Drug

Any chemical that affects the functions of the body

Binge drinking

The consumption of a large amount of alcohol over a short period of time