B1 - Cell Biology Flashcards
(20 cards)
Compare the structures found in prokaryotic and eukaryotic cells.
Eukaryotic cells have a nucleus and membrane-bound organelles; prokaryotic cells (e.g., bacteria) do not and have circular DNA and plasmids.
What is the function of the nucleus in a eukaryotic cell?
It controls cell activity and contains genetic material arranged as chromosomes.
Describe the roles of mitochondria and ribosomes.
Mitochondria release energy during aerobic respiration; ribosomes are the site of protein synthesis.
What subcellular structures are present in plant cells but not animal cells?
Cell wall, permanent vacuole, and chloroplasts.
How are sperm cells specialised for their function?
They have a tail for movement, mitochondria for energy, and enzymes in the acrosome to digest the egg membrane.
Explain how root hair cells are adapted for absorbing water and minerals.
They have a large surface area, thin walls, and no chloroplasts.
What is the function of xylem and phloem cells, and how are they adapted?
Xylem transports water (hollow, lignified walls); phloem transports sugars (companion cells, sieve plates).
What is differentiation, and when does it mainly occur?
Differentiation is the process where cells become specialised; in animals, it mainly occurs during early development.
What is the difference between light and electron microscopes?
Electron microscopes have higher resolution and magnification, allowing you to see smaller structures like ribosomes.
How do you calculate magnification in microscopy?
Magnification = image size ÷ actual size.
Describe the method for preparing a slide to view onion cells under a microscope.
Peel epidermis, place on slide, add iodine stain, cover with coverslip, and observe using low to high power.
What is the cell cycle, and what key process happens in mitosis?
The cell cycle includes growth, DNA replication, and division; in mitosis, a cell divides into two identical daughter cells.
What is the role of mitosis in the body?
Growth, repair, and asexual reproduction.
What are stem cells and where are they found?
Undifferentiated cells found in embryos (can become any type of cell) and adult bone marrow (fewer types).
What are the potential uses of stem cells in medicine?
Treating conditions like diabetes and paralysis by replacing damaged cells.
What are the ethical issues surrounding embryonic stem cells?
Some believe it is wrong to use embryos as it destroys potential life.
What is therapeutic cloning?
A technique used to create genetically identical stem cells
How do stem cells in plants differ from those in humans?
Meristem cells in plants can differentiate throughout the plant’s life and can be used to clone plants.
Why is diffusion important in cells?
It allows substances like oxygen and carbon dioxide to move across cell membranes for respiration and gas exchange.
What factors affect the rate of diffusion?
Concentration gradient, temperature, and surface area.
