B2.1 Flashcards
Define diffusion
The net movement of molecules from an area of high concentration to an area of low concentration down their concentration gradient.
How does temperature affect diffusion?
As the temperature increases, the rate of diffusion increases as the particles have more kinetic energy and move faster.
How does the concentration gradient affect diffusion?
The greater the concentration gradient (the difference between the two areas), the faster the rate of diffusion.
How does the surface area of the membrane affect diffusion
If the surface area increases so does the rate of diffusion as there is more space for the particles to move through.
Define osmosis
The net movement of water molecules from a high water potential to a low water potential down their concentration gradient across a partially permeable membrane.
Define active transport
The movement of molecules from a low concentration to a high concentration against their concentration gradient using energy.
Describe mitosis (including the cell cycle)
- The chromosomes are replicated
2, The chromosomes line up in the middle - The chromosomes are pulled apart
- Membranes from around the chromosomes and the cytoplasm divides.
- The two cells then continue growing,
Describe cell differentiation
Differentiation is where cells become specialised for a particular function.
How are sperm cells specialised to their function?
Large tail for movement
Acrosome(containing enzymes) to digest the egg membrane
Lots of mitochondria for energy
Haploid nucleus
How are nerve cells specialised to carry impulses?
They have a long axon to transport the impulse long distances
Contain extensions to connect to other nerve cells and contain neurotransmitters to transmit the impulse
How are root hair cells specialised to take up water and minerals?
They have lots of mitochondria to generate energy
They have a large surface area for faster diffusion.
What are stem cells
Stem cells are undifferentiated cells and can develop into lost of different types of cells.
Where are animal stem cells found?
Animal stem cells are found in embryos and in the bone marrow
What is the difference between adult and embryonic stem cells?
Embryonic stem cells can differentiate into any type of cell whereas adult stem cells can only differentiate into cell types from the tissue the stem cells are in.
Where are plant stem cells found?
Plant stem cells are found in meristematic tissue
