In human cells, what is a chromosome?
a structure found in nuclei, containing a DNA molecule
What type of cell division forms two identical daughter cells?
In which stage of the cell cycle are the chromosomes duplicated?
In which stage of the cell cycle, at the end of mitosis, does the one cell divide into two?
What term describes a cell that has two sets of chromosomes?
Where are plant meristems found?
tips of plant shoots and roots [also just inside bark of trees]
What happens in a plant meristem?
Cells divide rapidly by mitosis as the plant grows
What happens during cell differentiation?
Cells develop special features that help them carry out a particular function.
Why is cell differentiation important to plants and animals?
Specialised cells are more effective at carrying out different functions in the body.
A root hair cell is a specialised cell. What is its function?
to absorb water and dissolved mineral salts from the soil
How is a root hair cell specialised to carry out its function?
It has a long extension into the soil that increases the surface area for absorption
Explain how one specialisation of a xylem vessel helps it carry out its function.
any one from: thickened wall to prevent collapse of tube/withstand pressure of water; no cell cytoplasm and lost cell walls to form long tubes through which water flows up the plant; small holes in thick cell wall so water can pass into and out of the vessel from surrounding cells
Name one feature, other than mass, that could be measured to show growth in a plant.
any suitable measure that will show change over time, such as: height, tree girth, leaf area, number of leaves
Name the type of cell division that cells use to make identical copies of themselves.
What type of cell has the ability to differentiate into specialised cells?
In what organ system would you find nerve cells?
the nervous system
Are nerve cells diploid or haploid?
What part of a nerve cell contains chromosomes?
What part of a nerve cell makes proteins?
Nerve cells require a lot of energy. What cell structure would you expect them to have a lot of?
What is a nerve cell specialised to do?
carry electrical signals/impulses
List your senses.
touch, hearing, sight, taste, smell, balance, temperature and plenty of others
State the name of one organ in the nervous system.
brain, spinal cord or nerves or a named sense organ
Triple Only- What type of cells is the brain mainly made up of?
neurones, nerve cells
Triple Only-What part of the brain controls our senses and emotions?
Triple Only-State one thing that the cerebellum controls.
balance, posture or fine motor movements)
Triple Only-Where is the medulla oblongata in relation to the spinal cord?
at the top of the spinal cord
Triple Only-What part of the brain controls the rate of the heart?
Triple Only-What part of the brain stores our memories?
Triple Only-Apart from bundles of neurones, what else does a nerve contain?
Triple Only-What name is given to an electrical signal transmitted by a neurone?
Triple Only-What part of the brain controls the rate of breathing?
Triple Only-Which cerebral hemisphere receives information from the right eye?
What type of cells detect stimuli?
In which sense organ would you find receptor cells that detect light waves?
What are the electrical signals used in the nervous system called?
List, in order, the organs that an impulse goes through from the hand to the brain.
nerve(s), spinal cord
What are the two long ‘arms’ of a sensory neurone called?
dendron and axon
List, in order, the parts of a sensory neurone that an impulse goes through.
dendrite, dendron, axon, axon terminal
Why are sensory neurones so long?
to carry impulses quickly over long distances
What is the name of the fatty sheath that surrounds dendrons and axons?
What does the myelin sheath do?
speeds up transmission of impulses, insulates neurones from each other
Where in the eye are receptor cells for light found?
For short-sighted people where is the distant object focused?
In front of the retina. The eyeball is too long.
How can you fix short sightedness?
A diverging lens
For long-sighted people where is the distant object focused?
Focused behind the retina because the eyeball is too short.
How to correct long-sightedness?
Use a converging lens.
How does one get cataracts?
A protein builds up inside the lens and makes it cloudy.
Replace the cloudy lens with a new one.
What are wrong with colour blind people?
Some cones don’t work properly.
Shades of light and dark
Where are the cones and rods found?
What do ciliary muscles do?
Make the lens fatter to focus light form near objects and thinner to focus light from distant objects.
What does the lens do?
Fine-tunes the focusing of the cornea.
What does the cornea do? (Clear and colourless covering that focuses the light)
Bends (refracts) light rays to bring them together
What is the pupil?
The dark area in the middle of the eye, and is where light enters.
What does the iris do?
Controls the amount of light entering the eye. Constricts the pupil, decreases the diameter. Or dilates it, makes it bigger.
What is the optic nerve? And what does it contain?
Connects the eye to the brain. The information of all the cones is processed into full colour vision at the back of the cerebral hemispheres.
A bundle of neurones.
It is a sensory neurone.
What is the retina?
The eye is a sense organ that contains receptor cells found in a layer called the retina.
What does the 25th percentile show on a percentile growth chart of a babies masses?
25% of the babies masses will be below the 25th percentile line.
How do cancer cells and tumours occur?
When cells undergo uncontrollable cell division.
Growing lumps of cells are tumours that can damage the body and can result in death.
Nucleus breaks down and spindle fibres appear.
At the end of it the chromosomes are lined up on the spindle fibres across the middle of the cell.
Chromosome copies are separated and moved to either end of the cell on spindle fibres
Membrane forms around each set of chromosomes to form nuclei.
Examples of asexual reproduction?
Strawberry plants(runners), potatoes (tubers).
What is reproduction with one parent
Sex cells divide by what?
What does skin cells divide by?
Which is quicker asexual or sexual reproduction?
Asexual, usually chosen over sexual if can do both.
PET scanners use and do what?
Show the more active parts of the Brian.
What do motor neurones do?
They carry signals to effectors like muscles and glands.
What do CT scans use and do?
Show the shapes of structures in the brain.
How to treat brain tumours?
Tumours can be killed using radiotherapy (high-energy X-ray beams) and chemotherapy (injecting drugs that kill actively dividing cells).
Can cause damage to the brain though.
Why might the chemotherapy not work?
Blood-brain barrier - a natural filter that allows only certain substances to get from the blood to the brain.
Electrical impulses travel to the spinal cord in a …
Spinal cord damage can cause loss of legs and arms what is this called and are there any treatments?
There are no adult stem cells that can differentiate into neurones in the spinal cord, and so new neurones cannot be made to repair damage.
What diffuses across a synapse gap?
What is a synapse?
A neurone meeting another neurone.
What is Accomodation?
Accommodation is the process of changing lens shape in order to focus on an object as its distance from the eye changes.
What is the fnction of platelets?
To clott the blood near a wound and seal it up, this also stops infection and bleeding.