April Test 2 Flashcards
What is an allele?
Different versions of the same gene
If the sperm contains X chromosomes what will the gender be?
Girl
If the sperm contains Y chromosomes what gender will it be?
Boy
A dominant allele is shown how?
Capital letter
How is a recessive allele shown?
Lowercase letter
In blood types,
Ao will be =
Bo will be =
oo will be =
AB will be =
A
B
o
AB
Blood types A and B are equal strength, what is this called?
Codominant
If two of the same allele are paired up what is it called?
Homozygous
If two different alleles are paired up what is it called?
Heterozygous
What is a genotype?
The set of genes RESPONSIBLE for a particular trait
What’s a phenotype?
The characteristics of a trait
What is a zygote?
When male and female gametes combine
What chromosome does the egg only carry?
X
What is a genome?
All the DNA in an organism
What is the spinal cord?
A long column of neurones that runs down the spine
What does the spinal cord do?
Relays info between the brain and the rest of the body
Give a function of the cerebellum
Responsible for balance
Give a function of the medulla oblongata
Controls unconscious activities
What does a CT scanner do? What does it NOT do?
Uses X-rays to produce an image of the brain
Does not show the functions of brain parts
What does a PET scan do?
Use radioactive chemicals to show which parts of the brain are active
Why is it hard to repair damage to the nervous system?
Neurones don’t repair themselves
What are sensory receptors?
Groups of cells that can detect a change in the environment (a stimulus)
Explain how we react to a stimulus
- When the stimulus is detected, the info is converted to an electrical impulse and sent along sensory neurones to the CNS
- The CNS decides what to do and impulses travel along relay neurones
- The info is sent to a muscle or gland along a motor neurone and the muscle or gland reacts accordingly
What do dendrites and dendrons do?
Carry impulses TOWARDS the body
What do axons do?
Carry nerve impulses AWAY from the cell body
Explain the sensory neurone
- one long dendron carries impulses from receptor cells to the cell body
- one short axon carried impulses from there to the CNS
Explain the motor neurone
Many short dendrITES carry impulses from the CNS to the cell body
One long axon carried them from there to the effector cells
Explain the relay neurone
- many short dendrITES carry impulses from sensory neuromas to the cell body
- an axon carries impulses from there to the motor neurone
What is the connection between two neurones called?
A synapse
What is the nerve signal transmitted by?
Neurotransmitters
Explain how a reflex happens
- Injury happens
- Pain receptor is stimulated
- impulse travels along sensory neurones
- Impulses pass along a relay neurone
- Impulses travel along a motor neurone
- Impulses reach muscle and it contracts
What does the cornea do?
Bends light into the eye
What does the iris do?
Controls how much light enters the pupil
What does the lens do?
Bends light
What does the retina do?
Detects light
How do we look at close and distant objects?
Close-
Ciliary muscle contracts
Suspending ligament slackens
Lens becomes more rounded
Light is refracted more
Distant is opposite ^
How is short sightedness and long sightedness caused?
When the lens is the wrong shape
