GCSE Combined Science Biology

What do all cells have?

Nucleus, Cytoplasm, Cell Membrane, Mitochondria, Ribosomes

What do only plant and algal cells have?

A Cellulose Cell Wall (sometimes Chloroplasts and a Vacuole)

What do Eukaryotic Cells have?

Cell Membrane, Cytoplasm, Genetic Material enclosed in a nucleus,

What are Prokaryotic Cells?

Cytoplasm and a cell membrane surrounded by a cell wall. Genetic Material is not in a nucleus, but in a single DNA loop. May also contain plasmids. E.g. Bacteria

What is Diffusion?

Diffusion is the spreading out of particles of any substance in a solution or gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Give four examples of dissolved substances which move in and out of cells by diffusion

Glucose, Urea, Oxygen, Carbon Dioxide.

What is Osmosis?

The movement of water from a dilute to a more concentrated solute solution through a partially permeable membrane.

What is Active Transport?

The movement of substances from a more dilute solution to a more concentrated solution. This uses energy from food in respiration.

What is a tissue?

A group of cells with a similar structure and function

What is an organ?

A collection of tissues performing a specific function.

What is the Benedict's test for sugars?

They turn blue Benedict's solution brick red on heating

What is the ethanol test for lipids?

Ethanol will go milky white in the presence of lipids.

What is the Biuret test for Protein?

Biuret turns from blue to purple in the presence of proteins.

What do Carbohydrases break down?

Carbohydrates to simple sugars.

What do Proteases break down?

Proteins to Amino Acids

What do Lipases break down?

Lipids to Fatty Acids and Glycerol

What is the function of Bile?

Bile is produced by the liver and stored in the gall bladder and neutralises acid and emulsifies fats.

What is Plasma?

Plasma has blood cells suspended in it and transports proteins and chemicals around the body.

What is Haemoglobin?

It binds to oxygen to transport it from the lungs to tissues.

What do white blood cells do?

Protect against infection?

What are platelets?

Cell fragments that start the clotting process at wounds.

What are the capillaries there for?

Substances diffuse in and out of the blood

What kind of circulatory system do humans have?

A double circulatory system

What do stents do?

Keep narrowed or blocked arteries open.

What do statins do?

Reduce cholesterol levels reducing the risk of coronary heart disease.

What is the resting heart rate controlled by?

A group of cells in the right atrium form a natural pacemaker.

What are artificial pacemakers used for?

They're used to correct irregularities in the heart rhythm.

What are artificial hearts used for?

Keep patients alive while they wait for a transplant or to allow their own heart to rest.

What do the alveoli do?

Provide a large surface area and a rich supply of blood capillaries, so gas can diffuse efficiently.

What does xylem tissue do?

Transports water and mineral ions from the roots to the stems and leaves.

What does phloem do?

Transport dissolved sugars from the leaves to the rest of the plant.

What is transpiration?

Loss of water vapour from the leaves through the stomata (open for carbon dioxide for photosynthesis). Guard cells control this.

What are communicable diseases caused by?

Pathogens (microorganisms) which include bacteria, viruses, fungi and protists.

How do Bacteria make you feel ill

Produce toxins

How do viruses make you ill?

Live and reproduce inside your cells, causing cell damage

Name four ways in which the spread of disease can be prevented

Simple Hygiene, Destroying Vectors, Vaccination and Isolation

Measles Virus

Droplet infection.
Causes fever and a rash
Isolation and Vaccination

HIV

Flu-like illness
Attacks body's immune cells
AIDS occurs when the system become so damaged it can't deal with cancers or infections/

Tobacco Mosaic Virus

Spread by contact and vectors
Damages leaves, reduces photosynthesis. No treatment.
Spread controlled by field hygiene and pest control.

Rose Black Spot

Spread by wind and water.
Damages leaves so they drop off, affecting photosynthesis.
Spread controlled by removing affected leaves and chemical sprays.

Malaria

Parasitic Protists spread by female mosquitos.
Damages blood and liver cells, causes fever and shaking.
Prevent vectors from breeding, mosquito nets.

How do white blood cells defend against pathogens?

Ingest and destroy them or by making antibodies and antitoxins.

What is vaccination?

Introducing dead of inactive small amounts of pathogens into your body to stimulate white blood cells to produce antibodies.

What are new drugs tested for?

Efficacy, Toxicity, Dosage

What is preclinical testing?

Testing in a lab on cells, tissues and live animals.

What are clinical trials?

Healthy volunteers and patients. Low doses are used for safety, followed by higher doses to test for optimum dose.

What are benign tumours?

Form in one place and don't spread to other tissues.

What are malignant tumours?

Invade neigbourhing tissues.

What can smoking cause?

Cardiovascular disease including coronary heart disease, lung cancer, and lung diseases such as bronchitis and COPD.
A fetus exposed to smoke has restricted oxygen which can cause premature birth, low birthweight or stillbirth.

Alcohol

Can damage the liver and cause cirrhosis and liver cancer.

Photosynthesis

Endothermic reaction. Carbon dioxide + water (light) - glucose + oxygen

What can the rate of photosynthesis be affected by?

Light intensity, temperature, level of Carbon Dioxide and Chlorophyll.

What do plants use glucose for?

For Respiration
Convert to insoluble starch for storage
To produce fats or oils for storage
Produce cellulose for cell walls
Produce amino acids for photosynthesis (also need nitrate ions)

Cellular Respiration

Exothermic Reaction
Aerobic is Glucose + Oxygen - Carbon Dioxide + Water

Body Responses to Exercise

Increase in heart/breathing rate and in breath volume
Glycogen stores in the muscles are converted to glucose for cellular respiration
Flow of oxygenated blood to muscles increases

This happens to increase the rate of supply of glucose and oxygen and removal of carbon dioxide.

Anaerobic Respiration

Respiration without oxygen. In animal cells, glucose is incompletely broken down to form lactic acid. Transfers less energy.

What is oxygen debt?

The amount of oxygen needed to break down lactic acid which has built up.

Anaerobic respiration in plant cells

Production of Ethanol and Carbon Dioxide.

What is Metabolism?

Sum of all reactions in the body, including conversion of glucose to starch, glycogen and cellulose, formation of lipid molecules, use of glucose and nitrate ions to form amino acids (which are used to synthesise proteins and breakdown excess proteins to form urea).

What does blood flowing through the muscles do during anaerobic respiration?

Transports lactic acid to liver where it is converted to glucose.

What is homeostasis?

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

What does Homeostasis control?

Blood glucose concentration, body temperature, water levels.

What does the nervous system do?

Uses electrical impulses to enable you to react quickly to surroundings and coordinate your behaviour.

What are receptors?

Cells which detect stimuli (changes in the environment)

How is a reaction triggered?

Impulses from receptors pass along sensory neurones to the brain or spinal cord (CNS). Brain coordinates response and impulses are sent along motor neurones from the brain to effector organs.

What are reflexes?

Automatic and rapid reactions which don't involve conscious parts of the brain. Involve sensory, relay and motor neurones. Control breathing, digestion, avoiding danger

What are the main stages of a reflex arc?

Stimulus
Receptor
Sensory Neurone
Relay Neurone
Motor Neurone
Effector
Response

What is the endocrine system?

Glands that secrete chemicals called hormones directly into the bloodstream. Blood carries the hormone to a target organ where it produces an effect. Slower but longer lasting

What is the pituitary gland?

Master gland which secretes several hormones into the blood.

Name the key Endocrine glands

Pituitary, Thyroid, Pancreas, Adrenal, Ovaries and Testes

Blood glucose concentration?

Pancreas produces insulin which allows glucose to move from the blood into the cells and to be stored as glycogen in the liver and muscles. Also produces glucagon which allows glycogen to be converted back into glucose and released back into blood. Negative Feedback Cycle

What is type 1 diabetes?

Blood glucose may rise to fatal levels because pancreas does not secrete enough insulin.

What is type 2 diabetes?

Body stops responding to its own insulin.

How can Type 1 diabetes be controlled?

Insulin injections to replace hormone not made.

How can Type 2 diabetes be controlled?

Carbohydrate controlled diet, more exercise. Drugs may be needed

What does Thyroxine do?

Stimulates basic metabolic rate. Growth and development

What is Adrenaline?

Produced in times of fear/stress. Increases delivery of oxygen and glucose to brain, preparing body for fight or flight.

Difference between Thryoxine and Adrenaline

Thyroxine is controlled by negative feedback.

What is oestrogen?

Main female reproductive hormone produced by ovary. Stimulates eggs to mature in the ovary (one is released every 28 days at ovulation)

What is testosterone?

Main male reproductive hormone produced by testes. Stimulates sperm production.

What is IVF?

FSH and LH are used to stimulate maturation of eggs. Eggs are collected, fertilised and allowed to start development. They're then replaced in the uterus. Physically emotionally stressful, unsuccessful, can lead to risky multiple births.

What is asexual reproduction?

No fusion of gametes, only one parent. No mixing of genetic information, leading to genetically identical offspring - mitosis.

What is sexual reproduction?

Fusion of male and female gametes formed by meiosis. Meiosis leads to the formation of non identical cells. Mixing of genetic information that leads to variation.

What happens in Meiosis?

The genetic material is copied and then the cell divides twice to form four gametes, each with a single set of chromosomes.

What is a genome?

The entire genetic material of an organism.

What is a gene?

A small section of DNA on a chromosome. Each gene codes for a particular sequence of amino acids to make a specific protein.

What is a homozygote?

An individual with two identical alleles for a characteristic.

What is a heterozygote?

An individual with different alleles for a characteristic.

What is a genotype?

Describes the alleles present regarding a particular characteristic.

What is a phenotype?

The physical appearance of an individual regarding a particular characteristic.

What is a dominant/recessive allele?

A dominant allele is always expressed in the phenotype, even if only one is present in the pair.

A recessive allele is only expressed if two are present.

What are the sex chromosomes in a human female?

XX

What are the sex chromosomes in a male female?

XY

Is polydactyly dominant or recessive?

Dominant - can be inherited from either or both parents.

Is cystic fibrosis dominant or recessive?

Recessive - must be inherited from both.

What is the theory of evolution?

All species have evolved from simple life forms that first developed over 3 billion years ago.

What is genetic engineering?

Genes transferred to the cells of animals and plants at an early stage so they develop desired characteristics.

How does genetic engineering work?

Genes from chromosomes of humans and other organisms are cut out using enzymes and transferrred to cells of other organisms using a vector (usually a bacterial plasmid or virus)

What are fossils?

The remains of organisms from millions of years ago that can be found in rocks, ice, other places.

How are they formed?

The absence of decay, parts replaced by minerals as they decay, preserved traces or organisms.