topic 2 Flashcards
What is the cell cycle?
A series of stages a cell goes through to grow and divide, including growth, DNA replication, and mitosis.
Give three uses of mitosis in organisms.
Growth, repair and asexual reproduction.
Name the four stages of mitosis and describe what happens in each.
1) Prophase – chromosomes become visible
2) Metaphase – chromosomes line up in the middle
3) Anaphase – chromosomes pulled apart to opposite ends
4) Telophase – new nuclei form
True or false: “The cells produced at the end of mitosis are identical to each other and the parent cell.”
True – they are genetically identical.
How do animals grow?
By increasing cell number through mitosis and then cells differentiate to become specialised.
What major illness can result from uncontrolled cell division?
Cancer – caused by cells dividing too quickly and forming tumours.
How is a percentile chart used to monitor growth?
A child’s height or weight is plotted to compare to others their age. Falling below or above expected percentiles may suggest a growth issue.
What is a stem cell?
An undifferentiated cell that can become different types of specialised cells.
How are embryonic stem cells different from adult stem cells?
Embryonic stem cells can turn into any cell type; adult stem cells are more limited.
What are meristems and where are they found?
Meristems are regions in plants (like shoot and root tips) where stem cells divide for growth.
What are the potential benefits of stem cells in medicine?
They could treat diseases like diabetes, repair damaged tissues, and replace faulty cells.
Give three potential risks of using stem cells in medicine.
1) Risk of cancer from uncontrolled growth, 2) infection from contamination, 3) immune rejection.
What does the cerebrum do?
It controls movement, senses, intelligence, personality
What does a PET scan show?
Brain activity and which parts are working by detecting radioactive glucose use.
Why is treating the brain and spinal cord difficult?
They are delicate, hard to access, and damage can be permanent or worsen symptoms.
What does the myelin sheath do?
It insulates the axon and speeds up the electrical impulse.
What is a synapse?
A tiny gap between neurones they are essential for communication within nervous system.
What do neurotransmitters do?
They transfer the signal across the synapse from one neurone to the next.
What is a reflex arc?
A fast, automatic response that bypasses the brain to protect the body.
Why are reflexes faster than normal responses?
They don’t involve the brain – the signal goes through the spinal cord.
What does the cornea do?
refracts light as it enters the eye
What does the lens do?
focuses light onto the retina
Which part of the eye controls how much light enters the pupil?
The iris – it contracts or relaxes to adjust pupil size.
How are rods and cones different?
Rods detect DIM light and black and white light
Cones detect BRIGHT light and colour
How is short-sightedness treated?
With a concave lens that spreads out light so it focuses correctly on the retina.
Why is there no cure for colour blindness?
It’s a genetic condition affecting cone cells – current treatments can’t fix faulty genes in the retina.
What is a cataract?
A cloudy patch on the lens that stops light reaching the retina clearly, causing blurry vision.
