Year 10 Science Semester 2 Exam

Cellular pathogen

Either uni or multicellular, Can replicate on their own, Can be classified as microscopic or macroscopic, prokaryotic or eukaryotic.

Non-cellular pathogen

Require a host-cell to reproduce, Sessile - cannot move themselves
Have no metabolism, are Made up of just nucleic acid (DNA or RNA) or protein
Multiplies inside the cell and then bursts out of the cell (killing it) and infects other cells

bacteria

Microscopic, Prokaryotic pathogen (unicellular), can be hard for our body to recognise, Some don't need oxygen to survive, Can use antibiotics to treat
Eg tetanus, meningitis, whooping cough, plague

fungi

Generally microscopic, Eukaryotic pathogens (uni or multicellular), Includes yeast and mould, They secrete digestive enzymes to breakdown organic matter, spread via spores. Eg Tinea, Thrush, anthrax

parasite

Macroscopic, Eukaryotic, Large eukaryotic organisms, Live and feed on/in the host
and Require a host to survive. Eg ringworm, fleas, ticks, botfly

Viruses

Smaller than bacteria, Inside a host cell it is called a virus, When outside of a host cell it is called a virion. Eg chicken pox, HIV, influenza, measles

Prion

Smallest known pathogen, Made of protein, Affects the brain and is fatal, When a normal protein comes into contact with a prion it causes the protein to unfold and refold abnormally. Eg mad cow disease

pathogen

Pathogens are anything that causes disease. These can be cellular or no cellular. Eg: Bacteria, fungi, prions. Enter through any opening in the body.

disease

any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury

Steps for infection to become disease

The pathogen enters the body and reaches target
It overcomes the body's defence
It is established in 1 or more sites
It multiplies rapidly (harms host/produces symptoms)

Infectious diseases

Transmissible disease or communicable disease.

non-infectious
disease

Non-communicable disease. Do not involve pathogens.

symptomatic

Have the disease and show the symptoms.

Asymptomatic

Are infected but never show signs of the disease

transmission

passage or transfer, as of a disease from one individual to another. Can occur through direct contact, exchange of fluids, contamination, airborne, vector.

transmissible

Can be passed on from person to person.

environmental disease

Caused by environmental factors

nutritional deficiency

Caused by not having a balanced diet

inherited disease

Result of alleles mutating or chromosomal abnormalities

autoimmune disease

When our body does not recognise our own cells as 'self' and therefore attacks them. Eg lupus, MS

eukaryotic

Membrane-bound organelles, DNA is found in the nucleus and is linear, uni or multicellular

Prokaryotic

No membrane-bound organelles, DNA is found in a nucleoid and is circular, Uni cellular only. Bacteria-only

lymphatic system role

transports white blood cells (WBC) to the lymph nodes. Invading pathogens are transported in the lymph to the lymph nodes. Here bacteria, viruses and cancer cells are trapped and destroyed by phagocytes and WBC.

Lymphatic system -structure

The lymphatic system is made up of:
lymph
lymphatic vessels
primary and secondary lymphoid organs and tissues

phagocytes

A type of immune cell that can surround and kill microorganisms, ingest foreign material, and remove dead cells

lymph nodes

Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease

innate immunity

Non-specific or natural immunity. 1st and 2nd lines of defence. Immediate protection against pathogens, No memory, Attacks all pathogens the same way

adaptive immunity

Specific or acquired immunity. 3rd line of defence. Specific: recognises each pathogen and knows what action to use. Memory: remembers previous pathogens (immunological memory) and is able to provide a more rapid response should they infect again

Lines of defence

First: Physical, Chemical, Microbiological
Second: White blood cells and inflammation
Third: T and B cells

First line of defence

Physical, chemical and microbiological

physical

Intact skin, Hairs in nostrils

chemical

Secretion (tears and sweat), mucous membranes, stomach acid

microbiological

Good bacteria

Second line of defence

White blood cells and inflammation

WBCs

Phagocytes and neutrophils: engulf pathogens. When WBC do this, they die

inflammation

Affected area becomes red, hot, pain and swollen→ damaged cells release a chemical (histamine) that causes an increased amount of blood to flow to the inflamed area.

Third line of defence

T cells and B cells

T cells

Mature in the Thymus. WBC specifically fight viruses

B cells

Mature in the Bone marrow. WBC specifically fight bacteria. Through the use of antibodies

pandemic

Global outbreak of a disease refers to the spread not the severity. Eg Spanish flu

Conditions needed for a pandemic

New pathogen appears in an area which has not seen it before, Easy transmission, Spread is an uncontrolled

Epidemic

Widespread occurrence of a disease that is restricted geographically, and Concern that it can become pandemic. Eg Ebola

vaccine

Vaccines are chemicals that make your body think it has faced a pathogen. Created by taking a small part of the poison produced by the pathogen and making it inactive or attenuated. Creates a memory in your body in case you ever fight the real pathogen.

herd immunity

For an immunisation program to be successful, a sufficient number of people need to be vaccinated. More people vaccinated = less chance of a pathogen spreading.
It is essential for those who can't be vaccinated or who have suppressed immune systems. Eg newborn babies, the elderly, people suffering from an immune disease and people taking immunosuppressant medication

hygiene

Some diseases can be prevented by practicing good hygiene. Eg Salmonella enteritidis which causes gastro.
This can be prevented by:
- washing hands after handling animals or faeces
- Washing food prep areas
- Keeping meat products separate from each other

quarantine

By isolating infected people, the spread of disease can be stopped
Can be done at a national level Eg stopping people who have travelled to areas containing the ebola virus from entering Australia
Or at a local level Not going to school when you show signs of chickenpox

Antigen

Any substance that causes the body to make an immune response against that substance

Antibody

A protein made by plasma cells in response to an antigen

DNA

deoxyribonucleic acid
Made from Nucleotides
Codes for proteins that determine the characteristics of the organisms eg appearance, metabolism, behaviour, immune system
Formed by 2 complementary strands, a double helix twisted

Parts of a Nucleotide

A phosphate group, a sugar group (Deoxyribose), A nitrogenous base

What are the four nitrogen bases?

Adenine, Thymine, Guanine, Cytosine

What are the complementary base pairs

Adenine and Thymine
Cytosine and Guanine

Genes

Segments of DNA are connected together that carries the information for making all the proteins required by all organisms. Strictured as chromosomes

Chromosome

Small molecules of DNA that each have a set of genes on them.
Highly wound DNA
There are 46 chromosomes in each of the somatic cells (23 pairs)

Locus

Where each gene is located on a particular chromosome

Genomes

Total number of genes in an individual or cell
Complete set of DNA in an organism

Alleles

Different variants of each gene

Genotype

The allele combination you inherits (Letter codes)

Phenotype

The allele that you display/show (Hair)

Homozygous

Same alleles eg BB or bb

Heterozygous

Different alleles eg bb

Meiosis

Process used to make gametes

Gametes in animals

sperm and egg cells

Gametes in plants

Pollen and ova

Somatic cell

general term for all other cells in the body except sperm and eggs (not a sex cell)

Fertilisation

Process of two gametes coming together to form one cell

Zygote

First cell of a new individual. The cell will grow and divide

Mutations

Changes in nucleotide DNA sequences
Creates new allele or can alter allele or will be fatal or may be silent
Can occur in somatic cells or gametes

somatic mutation

affects body cells (Not inherited)

Germeline mutations

alter the gametes (Inherited)

Dominant allele

an allele that effectively overrules the recessive allele
expressed more strongly

recessive allele

a variety of genetic code that does not create a phenotype if a dominant allele is present
Non dominant

factors that mutate DNA

errors in cell replication
Radiation
Certain chemicals
Some viruses

Can switch a single base or alter a larger section of DNA

Gametes

Half of DNA found in somatic cells
Only one copy of every chromosome
each gamete = genetically different allele combination

Example of a muation

Down Syndrome
- Trisomy 21 (three copies of chromosome 21)
- Physical growth delays, characteristic facial features, mild-moderate intellectual disability

linked genes

genes located on same chromosome

Mutations can be...

beneficial (malaria resistance)
harmful (cystic fibrosis)
neutral (ability to smell ants)

Proteins

form parts of cells, regulate cell activities, help defend against disease

Mutagens

factors that cause mutations
UV light
Some viruses
Errors in replication
Some chemicals

How can meiosis cause mutations

When meiosis occurs, an extra gamete can be created which leads to trisomy. This can either be deadly or cause life long conditions

Pedigree key

Recessive identifier on pedigree

Parents dont show trait then child does

Dominant identifier on pedigree

Parents show the trait but the child does not

Punnet Squares

diagram showing the gene combinations that might result from a genetic cross

features of sexual reproduction

Allows adaption
Uses gametes
Leads to diversity
Slow
Occurs in humans and mammals
Not possible for an isolated individual to reproduce

Features of asexual

No gametes
only need one parent
Does not lead to diversity
Fast
Example: Daffodils and mushroom
Diversity limited which can lead to inability to adapt

physiological

having to do with an organism's physical processes

Hypothesis

Possible explanation or answer for something that has been observed

Independent Variable

is deliberately altered
Possible cause of the change

Dependent Variable

the one with the observable change
Relies on the independent variable to change

Fixed or Controlled Variables

kept constant

Extraneous Variables

variables you are not intentionally studying but may alter the experiment

Experimental Group

Maintained under normal conditions in all aspects except for the one variable being tested
Tests the effect of the dependent variable on the independent variable

Control Group

Assumed to be identical to the experimental group
Basis for comparison of all other observations

ERA

E - EMPIRICAL
R - RESEARCH
A - ACTIVITY

4 main ethical considerations

Confidentiality, Voluntary Participation, Withdrawal Rights, Informed Consent Procedures

Confidentiality

All personal information and responses must not be revealed without their permission.
Participants have the right to participate anonymously.

Voluntary Participation

Must be given the freedom to decline participation.
Participants must not be coerced, given inducements or threatened in any way.

Withdrawal Rights

Are free to withdraw (to leave) at any stage of the study so that their welfare is not compromised in any way.

Informed Consent Procedures

Potential participants need to decide whether to participate in an experiment after being informed of the nature and purpose of the research.
Their participation must be totally voluntary and their consent should be obtained in writing whenever possible.