Cells And Control Flashcards
What are the stages of the cell cycle and what happens in each?
- Interphase – Cell grows, DNA replicates.
- Mitosis – Nucleus divides.
- Cytokinesis – Cell splits into two genetically identical diploid cells.
Why is mitosis important for an organism?
Mitosis is important for growth, repair, replacement of cells, and asexual reproduction.
Why do organisms rely on asexual reproduction?
It is fast, requires one parent, and produces genetically identical offspring.
How does mitosis produce genetically identical diploid cells?
DNA is copied exactly in interphase, then evenly divided so both daughter cells receive identical chromosomes.
How do cancers grow?
Cancer is caused by uncontrolled mitosis, forming a mass of cells called a tumour.
What is growth in animals?
Growth is an increase in cell number and cell size.
Give examples of specialised animal cells and how their structures relate to function.
• Red blood cells: no nucleus, biconcave shape – carry more oxygen.
• Sperm cells: tail for movement, mitochondria for energy.
• Muscle cells: can contract to cause movement.
Why is cell differentiation important in animals?
It allows cells to become specialised for different functions, forming tissues and organs.
What are percentile growth curves used for?
They track a child’s height or weight over time to monitor normal development.
What are the stages of growth in plants?
- Cell division (mitosis) in the meristems
- Elongation – cells increase in length
- Differentiation – cells become specialised.
Give examples of specialised plant cells and their functions.
• Root hair cells: large surface area to absorb water/minerals.
• Xylem: hollow tubes to transport water.
• Phloem: carries sugars from photosynthesis.
Why is cell differentiation important in plants?
It produces specialised tissues like xylem and phloem for transport and support.
Where are stem cells found?
In embryos, bone marrow (adults), and meristems (plants).
What do stem cells do?
They can divide and differentiate into different types of specialised cells.
What is the difference between embryonic and adult stem cells?
• Embryonic stem cells: can become any cell type.
• Adult stem cells: more limited – can only become certain cells (e.g., blood cells).
Give medical uses of stem cells.
• Treat diabetes (make insulin cells).
• Treat paralysis (make nerve cells).
• Bone marrow transplants.
What are the benefits and risks of using stem cells in medicine?
Benefits: Treat incurable diseases, repair damaged tissue.
Risks: Ethical issues, possible rejection, may cause tumours if uncontrolled.
How can we evaluate stem cell use?
We compare benefits (e.g., saving lives) and risks (e.g., ethics, rejection, safety).
What are the parts of the nervous system?
• Central Nervous System (CNS): brain and spinal cord.
• Peripheral Nervous System: all other nerves.
• Effectors and receptors.
How does the nervous system detect stimuli?
Receptors in sense organs detect changes and send electrical impulses via sensory neurones to the brain/spinal cord.
What is the structure of sensory neurones?
Long dendron, cell body in the middle, long axon. Carries impulses from receptors to CNS.
How do impulses travel to and from the brain?
• Sensory neurones → CNS
• Relay neurones (in CNS)
• Motor neurones → Effectors.
How are sensory neurones adapted to their function?
• Long to carry signals quickly.
• Myelin sheath insulates and speeds up transmission.
• Many dendrites to connect to receptors.
How does the nervous system respond to stimuli?
CNS processes the impulse and sends a response via motor neurones to effectors (muscles/glands).
