Comprehensive A-Level Biology and Disease Flashcards

Tuberculosis

Bacterial disease that can infect humans, deer, cows, pigs, and badgers.

Kills the cells and tissues

Lungs are most often affected

Bacterial meningitis

Infection of the meninges- the membranes that surround the brain and the spinal cord

The membrane becomes swollen and may cause damage to the brain and nerves

Pathogen

Organism that causes disease

Two types of phagocytes

Neutrophils and macrophages

How to find pathogens

Phagocytes are attracted by:

Chemicals released from pathogens

Signals from damaged body cells

Viruses

Invade cells and takeover the genetic machinery and the other organelles of the cells

Caused the cells to manufacture more copies of the virus

The hostel eventually bursts releasing many new viruses which will infect healthy cells. Good night.

Why does the body need different types of white blood cells?

Different white blood cells have different functions so the body can destroy pathogens in more than 1 way

Explain why antibodies made for one pathogen may not work on another pathogen.

Antibodies are specific and each antibody has a shape that only fits one type of antigen on a pathogen

Phagocytosis

Non specific defence

Destroys many different types of pathogens

Tuberculosis treatment

Cured using antibiotics and prevented through vaccination.

Ringworm

A type of ringworm that thrives in warm, damp regions between the toes.

Ringworm symptoms

Causes the skin to crack and become scaly, causing itchiness and soreness.

Ringworm treatment

Can be cured using antifungal creams.

Ring rot

Caused by a bacterium that infects potatoes, tomatoes, and aubergines.

Ring of decay in the vascular tissue of a potato tuber or tomato accompanied by leaf wilting

AIDS

When the replicating viruses in the helper T cells interfere with the normal functioning of the immune system.

Attacks cells in their immune system and compromises the immune response

Tobacco mosaic virus

This virus infects plants, mainly tobacco plants.

Tobacco mosaic virus effects

Causes damage to the leaves, resulting in a mosaic pattern on their surfaces.

Causes mottling and discolouration of leaves

Influenza

A disease caused by a virus that infects the ciliated cells lining gas exchange surfaces.

Attacks respiratory system and causes muscle pains and headaches

Influenza risks

Young children, the elderly, and those who are immunocompromised are more at risk of severe symptoms.

Communicable disease

Diseases caused by pathogens: bacteria, viruses, protoctista, and fungi.

Potato blight

Caused by a protoctista.

Affects both leaves and potato tubers

Fungi

Eukaryotes that cause many plant diseases and can be either multicellular or single-celled.

Black Sigatoka

Caused by the Mycosphaerella fijiensis fungus, which infects bananas.

Black Sigatoka effects

The fungal hyphae cause damage to the leaves, causing them to turn black and prevent plant growth.

Protoctista

Eukaryotes that exist as single-celled organisms or cells grouped into colonies.

Pathogenic protoctista

Parasites that are usually transmitted via a vector, e.g., malaria is transmitted by mosquitos.

Rheumatoid arthritis

An example of an autoimmune disease where the immune system attacks the cartilage in joints.

Herd immunity

It is passed from mosquitos to humans when mosquitos bite and take blood from humans.

Direct transmission between animals

Includes direct contact, inoculation, and ingestion.

Indirect transmission between animals

Includes vectors, droplets, and fomites.

Plant disease defense mechanism

The carbohydrate becomes a barrier which prevents the pathogens from spreading to further cells.

Malaria

Parasite in the blood that causes headaches and fever and may progress to Coma and death

direct transmission

Direct physical contact such as touching a person who is infected or touching contaminated surfaces that harbour pathogens

E.g HIV ringworm athletes foot bacteria meningitis

Wash hands regularly, especially after using the toilet

Keep surfaces clean, especially door handles

Clean and disinfect cuts and abrasions

Sterilise surgical instruments

Use Condoms

Faecal- oral transmission

Drinking water or eating food contaminated by the pathogen

E.g food poisoning,cholera

Using human sewage to fertilise crops

Treatment of wastewater and treatment of drinking water

thorough, washing of all fresh food

Careful preparation and thorough cooking of all food

Droplet infection

Pathogen is carried in tiny water droplets in the air

E,g tuberculosis influenza

Cover your mouth when coughing or sneezing

Use a tissue and ensure the tissue is disposed of correctly

Transmission by spores

Resistant stage of the pathogen

Carried in the air or reside on surfaces or in the soil

E.g anthrax tetanus

Use a mask

Wash skin after contact with soil

Social factors affecting transmission

Overcrowding

Poor ventilation

Pool health

Poor diet

Homelessness

Indirect transmission

Some pathogens are transmitted indirectly via vector

A vector is another organism that may be used by the pathogen to gain entry to the primary host

Indirect transmission of plant pathogen

Result of insect attack

Spores or bacteria become attached to a borrowing insect such as a beetle which attacks an infected plant

When that beetle attack attacks another plant, the pathogen is transmitted to the uninfected plant

The beetle acts as a vector

Athletes foot

Growth of fungus under skin of feet

Callose

A polysaccharide that can be deposited at sieve plates in phloem, and other locations, in the plant to prevent pathogens spreading within them.

Mucous membranes

Line many body tracts, for example the trachea in the lungs.

Mucus

Produced by goblet cells, traps pathogens.

Lysozymes

This enzyme is found in tears in the eye and also in phagocytic white blood cells.

Expulsive reflexes

Reflexes such as sneezing, coughing, and vomiting.

Hydrolytic enzymes

Found in lysosomes, which digest pathogens.

Inflammation

Occurs in localized areas where damage to cells is detected, causing the area to become red, hot, sore, itchy, and swollen.

Histamines

Cause blood vessels to dilate and therefore more blood is flowing in this area.

Cytokines

Chemicals which attract phagocytes, which can engulf and destroy the pathogens.

Phagocytes

Cells that engulf and destroy pathogens.

Antigens

Trigger an immune response when detected by lymphocytes.

Chemical markers on the surface of cells

Protein/glycoprotein

Specific to each pathogen

T lymphocytes

A type of white blood cell that enables identification of cells as either 'self' or 'foreign' by the immune system.

Antigen-presenting cells

Any cell that presents a non-self antigen on their surface.

T helper cells

Have receptors on their surface that attach to antigens on APCs and become activated - clonal selection.

T regulator cells

Produce interleukins to activate B lymphocytes and stimulate macrophages for phagocytosis.

B lymphocytes

Made in bone marrow and mature in bone marrow; involved in humoral immune response and produce antibodies.

Humoral response

Involves the production of antibodies.

B memory cells

Remember specific antibodies for particular antigens.

Antibody structure

Antibodies have two binding sites and are flexible so they can clump pathogens together.

Passive immunity

Antibodies introduced into the body; plasma and memory cells not made as no interaction with antigen.

Opsonins

Antibodies act as opsonins when an antibody-antigen complex has been formed.

Proteins that attach to antigens on pathogens

Help phagocytes bind to the pathogen more easily

Make phagocytosis more effective

Phagosome

The vesicle formed around a pathogen inside a phagocyte.

Clonal selection

When immune cells with the complementary antigens or antibodies to the pathogen's antigens are activated in response to the pathogen.

Clonal expansion

When immune cells rapidly divide by mitosis.

Natural active immunity

Immunity created by own immune system after direct contact with pathogen through infection.

Artificial active immunity

Creation of antibodies and memory cells following introduction of an attenuated pathogen or antigens, e.g., vaccination.

Vaccination

Leads to the creation of antibodies and memory cells.

Polymorphic genes

A gene that has more than one allele.

Captive breeding

Breeding endangered species in zoos and other facilities to build a healthy population of the animals.

Mutation

Changes in the processes within an organism when pathogenic DNA mutates causing a change in shape of antigen.

Antigenic variability

Specific antibody no longer binds to new antigen

Epidemic

When a disease spreads rapidly on a national level

Pandemic

When a disease spreads rapidly on a global level

Antibiotic resistance

This is often caused by a mutation in the bacterium or receiving a copy of an antibiotic resistance gene from another bacteria - horizontal transfer.

Pharmacogenetics

By analysing your DNA, it can be possible to identify drugs that individuals will respond better to

Personalised medicines

Medicines tailored to individual genetic profiles

Synthetic biology

Using bacteria as medicine factories

Habitat

Includes examples such as the genetic engineering of bacteria to make human insulin

Environment

All the alleles in a population at a particular time

Gene pool

The number of different alleles in a population

Genetic diversity

Sharing of alleles from one population to another

Gene flow

A measure of the range of habitats

Habitat diversity

The number of different species within an area and their abundance to indicate biodiversity

Species diversity

This involves both species richness and species evenness

Species richness

A measure of the number of different species in a community

Species evenness

The relative abundance of each different species within a community

Community

The number of different species within an area and their abundance to indicate biodiversity

Diversity index

An index of diversity combines both the number of different species and the population size of each within a community

Random sampling

Method for random quadrat sampling using two tape measures at right angles to each other

Opportunistic sampling

Sampling organisms which are conveniently available, involves bias

Stratified sampling

Populations or habitats can be separated into groups to sample from

Systematic sampling

Identifying different areas within a habitat to sample

Impact of Agriculture on Biodiversity

Clearing land for agriculture results in the destruction of habitats

Reasons to maintain biodiversity

Reducing the number of habitats and food sources decreases biodiversity

Conservation methods

Economic reasons - deficient soil can reduce the ability to grow crops and make a profit, ecotourism

Hierarchy

Smaller groups arranged within larger groups with no overlap between groups

Taxon

The term for each group in a classification hierarchy

Binomial system

A universal naming system for species

Phylogeny

The change in allele frequency over many generations in a population

Types of variation

Intraspecific variation and interspecific variation