B1 Flashcards
What does magnification mean?
How much bigger a sample appears to be under the microscope than it is in real life
What does resolution mean?
The ability of a microscope to distinguish fine details and differentiate between two very close objects
Formula linking magnification, image size and real size
Magnification = Image Size ÷ Actual Size
Actual Size = Image Size ÷ Magnification
Image Size = Actual Size x Magnification
Number of micrometers (µm) in a millimeter (mm)?
1000 micrometers in a millimeter
Number of nanometers (nm) in a micrometer (µm)?
1000 nanometers in a micrometer
Organelles in an animal cell
Nucleus, Cell membrane, Cytoplasm, Mitochondria and Ribosomes
Extra Organelles in plant cells
Cell Wall, Chloroplasts, Permanent Vacuole
Function of a nucleus
Directs all the cells activities; contains the cells DNA
Function of cell membrane
regulates what enters and leaves the cell
Function of cytoplasm
Where chemical reactions take place
Function of mitochondria
Powerhouse of the cell; Where respiration occurs
Function of Ribosomes
Where protein are synthesised
Function of Chloroplasts
Site of photosynthesis; contains Chlorophyll - a green pigment
Function of Cell Wall
Protects, strengthens and supports the cell
Function of Vacuole
Filled with cell sap which helps keep the cell turgid
What are the two types of cells?
Prokaryotes and Eukaryotes
What are prokaryotic cells?
Bacterial cells; Cells without a nucleus
What are eukaryotic cells?
Cells with a nucleus and organelles
What is differentiation?
The process by which a cell changes to become specialised for its job
Function of root hair cells
To absorb water and mineral ions for the plant via osmosis
Adaptation of root hair cells
- Large surface area for water to move up the cell
- Have lots of mitochondria which release energy from glucose needed for active transport of mineral ions into the cell
- Have a large permanent vacuole that speeds up the movement of water by osmosis
Function of sperm cells
Contains genetic information in the nucleus; needed for fertilisation to occur
Adaptation of sperm cell?
- It has a long tail and a streamlined head to help it swim to the egg
- There are lots of mitochondria in the cell to provide the energy needed.
- It also carries enzymes in its head to digest through the egg cell membrane.
Function of nerve cells
To carry electrical impulses around the body
Adaptation of nerve cell
- Thin, long branches to carry impulses all around the body
- Branched connections at each end to allow electrical impulses to pass to other cells
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration; results in an equilibrium of particles; DOWN a concentration gradient; no energy needed (passive)
Where does diffusion occur?
Gas exchange in the lungs
What is osmosis?
Diffusion of WATER molecules across a partially permeable membrane (cell membrane) from an area of high to low concentration; DOWN a concentration gradient; no energy needed (passive)
Water molecules have an overall net movement if an area has a stronger concentration of solutes (salts dissolved in water)
Where does osmosis occur?
- Root hair cells (plants)
- Water going into blood in the intestines
What does turgid mean?
When cell walls become rigid due to high water content
What does hypertonic mean?
higher solute concentration, lower water concentration in a solvent
What does hypotonic mean?
lower solute concentration, higher water concentration in a solvent
What does isotonic mean?
equal solute and water concentration in a solvent
What is active transport?
The movement of ions or molecules across a partially permeable membrane (cell membrane) from a region of lower concentration to a region of high concentration; AGAINST a concentration gradient; requires energy from respiration (active)
Where does active transport occur?
- In root hair cells, moving mineral ions and water from the soil and into the plant
- In the gut where there is a lower concentration of nutrients in the gut and a higher concentration in the blood.
How does exchange occur?
- Diffusion
- Osmosis
- Active transport
Describe how a small object effects the relationship between surface area to volume ratio?
The SMALLER the object, the HIGHER the SA : V
- Shorter diffusion distance = more sufficient for exchanging materials
Describe how a large object effects the relationship between surface area to volume ratio?
The LARGER the object, the SMALLER the SA : V
- Larger diffusion distance = less sufficient for exchanging materials
What makes a good exchange surface?
- Large surface area
- Thin membrane surface
- Rich blood supply (maintaining steep concentration gradients)
