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Flashcards in B123 Deck (36)
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What is the function of a gene?

To code for a specific protein. Some are structural and make up the body. Others are functional, and do things. Like enzymes.


What is the difference between genotype and phenotype?

Genotype is the genes someone has. Phenotype are the characteristics someone shows.


Why do children look a bit like both their parents?

They inherit genes from both their parents, but only one copy from both. These mix up randomly, thus a child looks a little like both.


What is the difference between homozygous and heterozygous?

Homozygous = same alleles for a trait.
Heterozygous = different alleles for a trait.


Explain how alleles combine to produce a phenotype.

Two/One dominant alleles: Trait is shown.
One recessive: no trait shown.
Two recessive: trait is shown.


How do genes determine how gender develops?

The Y chromosome carries a gene which causes the production of a protein which itself causes testes to be produced. If it is not present, ovaries are produced.


What are the symptoms of cystic fibrosis?

Sticky mucus, breathing difficulty, chest infections, difficulty in digesting food.


What are the symptoms of Huntington's disease?

Tremors, clumsiness, amnesia, mood changes, poor concentration.


In what three ways can genetic testing occur?

When embryos are produced by IVF, they an be tested and selected.
Children and adults can be tested for diseases.
Children and adults can be tested before drugs a re prescribed.


What issues are associated with genetic testing.

Accuracy, safety, children, family, abortions, discrimination, insurance


What is a clone? How do they occur in nature?

A clone is a genetically identical organism.
They occur in nature in a few ways: Bacterial mitosis, greenflies, runners, bulbs,identical twins. They can also be produced artificially.


What is the difference between embryonic and adult stem cells?

Embryonic -> can be come anything. Totipotent.
Adult -> They can become some things, but not everything.


How can symptoms be caused?

By cell damage or toxins.


How do antibodies fight infection?

They either:
Mark microorganisms
Bind to and neutralise toxins
Kill bacteria directly.


How does vaccination work?

You are injected with a non-harmful form of a microbe. Your body produces antibodies to attack them. Your memory cells remember how to attack them so if you are infected, the antibodies are produced very quickly.


Why should we always finish antibiotics courses?

Antibiotics create a situation where resistant bacteria have an advantage, causing rapid evolution.


Describe the drug trial process.

They are developed using human cells, then tested on two species of mammal. They are then given to human volunteers and finally to sufferers of the disease to be cured. Blind trials, open-label trials, double-blind trials and placebos are all used.


How are the three blood vessels specialised for their own jobs?

Arteries have strong walls to deal with the high pressure.
Veins have valves to keep blood flowing correctly.
Capillaries have walls just a cell thick to allow easy diffusion.


How is blood pressure expressed?

Two values - a higher value when the heart contracts and a lower value when it relaxes.


What lifestyle factors can increase the risk of heart disease?

Poor diet, smoking, misuse of drugs, excessive alcohol drinking, stress


What is homeostasis?

Balancing inputs and outputs to maintain a constant internal environment.


What three things are invoked in a general negative feedback loop?

Receptor, processing centre, effector.


What are the inputs and outputs for water?

Inputs: drinks,food respiration
Outputs: sweating,breathing, faeces,urine


How do the kidneys control water?

They filter small molecules from the blood. They reabsorb a lot of things. Whatever isn't reabsorbed becomes urine.


What things affect the consistency of urine?

External temperature, exercise, intake of fluids and salts.


How do drugs affect ADH production?

Alcohol results in a large amount of more dilute urine.
Ecstasy results in small amount of more concentrated urine.


What is a species?

A group of organisms that can breed to produce fertile offspring.


What are the similarities and differences between natural selection and selective breeding?

Natural selection: characteristics that are good for survival.
Selective breeding: whatever humans want.


Contrast Darwin's and lamarck's ideas on evolution.

Darwin proposed evolution through natural selection. Lamarck proposed that if a characteristic was used a lot by an animal then it would be more developed. He was very wrong.


What does biodiversity include? Why is it important?

Biodiversity includes he number of different species, the range of species,a nd the variation within the species. It is important because we need resources to make food crops and medicines.