Cell Biology Flashcards
Define Diffusion
Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.
True or False: Diffusion only happens in gases?
False, it occurs in solutions and gases
What is the concentration gradient?
The difference in concentration
True or False: The bigger the concentration gradient, the faster the rate of diffusion.
True
How does the temperature affect the rate of diffusion?
A higher temperature will give a faster diffusion rate because the particles have more energy and will move around faster.
Cell membranes are semi-permeable. What does this mean?
It means they let some molecules through but not all molecules.
True or False: Dissolved substances can move in and out of cells by diffusion.
True
True or False: Particles can only move one way through a semi-permeable membrane
False, the movement is random so the particles can move both ways
What does a ‘net movement’ mean?
the overall movement of the particles
How does the surface area of the membrane affect the diffusion rate?
A larger surface means a higher diffusion rate because more particles can pass through at once.
Give three factors that can affect the rate of diffusion:
• Concentration gradient - the bigger the gradient, the faster the rate of diffusion
• Temperature - the higher the temperature, the faster the rate of diffusion
• Surface area of a cell membrane - the larger the surface area, the faster the rate of diffusion
Define Osmosis
Osmosis is the movement of water molecules across a partially permeable membrane from an area of high concentration to an area of lower concentration.
What is a hypotonic solution?
A solution with low solute concentration and a higher water concentration
What is a hypertonic solution?
A solution with a higher solute concentration and a lower water concentration
What is an isotonic solution?
A solution with the same solute concentration and the same water concentration in relation to another substance.
What are the two main stages of the cell cycle?
- Growth and DNA Replication
- Mitosis
What is the Cell Cycle?
The process by which cells divide to produce new cells
What happens during Growth and DNA Replication?
The cell increases its number of subcellular structures and the DNA Replicates to form two copies of each chromosome
What happens during mitosis?
- Chromosomes line up at the centre of the cell and are pulled apart by cell fibres. Two arms of each chromosomes go to opposite ends of the cell
- Nucleus divides and forms membranes around each new set of chromosomes which become the nuclei of each cell
- Cytoplasm and cell membrane divide and 2 new identical daughter cells are formed
What is active transport?
The movement of substances from dilute to a concentrated solution, against the concentration gradient
How is Active Transport important for plants?
It allows mineral ions to be absorbed into plant root hairs from dilute solutions in the soil.
How is Active Transport important in the body?
It allows sugar molecules to be absorbed from lower concentrations in the gut into the blood so it can be carried to
the cells for respiration
Where are Chromosomes found and what do they contain?
In the nucleus, they contain genes
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