B2.1 Flashcards
Diffusion
The overall movement of particles from a region of high concentration to a region of low concentration
Factor that affects the rate of diffusion: decreasing the distance the particles need to move
Takes less time to travel a shorter distance
Factor that affects the rate of diffusion: increasing the concentration gradient
The steeper the concentration gradient, the greater the net movement of particles
Factor that affects the rate of diffusion: increasing surface area
Allows more space for diffusion, so more particles can move in a period of time
Osmosis
A type of diffusion where the water molecules from a high water potential move to a region of low water potential
Water potential
The concentration of free water molecules
Turgid
Firm
A cell becomes turgid when the concentration of a solution outside it decreases (higher water potential). In this situation it may burst, known as lysis
Flaccid
Soft
A cell becomes flaccid when the concentration of the surrounding solution increases (lower water potential). In this situation the cell may collapse and crinkle. This is known as being crenated
Active transport
Allows cells to move substances from an area of low concentration to an area of high concentration
As the particles are going against their concentration gradient, energy is required
Key features of Active Transport
Particles are transported against their concentration gradient
ATP (energy) is required
Carrier proteins in the cell membrane bind to the substance and rotate, transporting it into the cell
Example of active transport
Digestion
Small intestines, carbs are broken down into glucose
Glucose is actively transported by the villi into the bloodstream
Mitosis
The process by which body cells divide
Cell cycle
The process of cell growth and division
First Stage of the Cell Cycle
Transcription
Second Stage of the Cell Cycle
Movement of chromosomes
The chromosomes line up across the centre of the cell
The two identical copies of each chromosome, formed when the DNA replicated, separate and move to opposite ends of the cell
Each end now contains a full set of identical chromosomes
Two new nuclei then form
Cell Differentiation
When a cell becomes specialised to perform a particular job
It’s structure changes so it’s better adapted to perform its function
This makes the entire organism more efficient, as life process are carried out more effectively
Sperm Cell adaptations
Flagellum - propels the sperm to the ovum
Lots of mitochondria - allows the flagellum to move rapidly
Acrosome - stores digestive enzymes which break down the outer layer of the ovum
Fat Cell adaptations
Small layer of cytoplasm surrounding a fat reservoir
They can expand up to 1000 times their original size as they fill with fat
Red Blood cell
Biconcave disks - increases surface area
Full of haemoglobin - binds to oxygen to form oxyhemoglobin
Non nucleus - saves space
Stem cell
An undifferentiated cell
Embryonic stem cell
Found in embryos
Can differentiate into all cell types
Adult stem cell
Found in various body tissues such as the brain, bone marrow, skin, and liver
Can differentiate into some cell types
Act as a repair mechanism for the body
Meristems
Stem cells in plants are found here
They have a small size, very thin walls, small vacuoles, and no chloroplast
Differentiated cell’s cannot divide as their cell walls are thick and rigid
