B1 Flashcards
What is a eukaryotic cell?
A cell with a nucleus. Plant and animal cells are eukaryotic.
What is a prokaryotic cell?
A small cell without a nucleus, it has a large ring of genetic information with other smaller plasmids around the cell. Bacterial cells are prokaryotic.
What organelles are in an animal cell?
A nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
What extra organelles do plant cells have?
A cell wall, a permanent vacuole and chloroplasts.
What is the function of the nucleus?
The nucleus holds genetic info and controls the activities of the cell.
What is the function of the cytoplasm?
The cytoplasm is where most chemical reactions of the cell occur.
What is the function of the cell membrane?
The cell membrane controls what goes in and out of the cell.
What is the function of the mitochondria?
The mitochondria releases energy through aerobic respiration.
What is the function of the ribosomes?
The ribosomes produce proteins via protein synthesis.
What is the function of a cell wall?
The cell wall maintains the shape of the cell and prevents the bursting of the cell. It is made from cellulose.
What is the function of the permanent vacuole?
The permanent vacuole holds cell sap
What is the function of the chloroplasts?
The chloroplasts contain chlorophyll that absorbs light for photosynthesis.
What is magnification?
How much bigger an object appears compared to it’s actual size.
What is resolution?
Resolution is how well you can distinguish between 2 objects close together (How detailed it is)
Magnification Formula
Magnification = Image size/ Actual size
Electron microscopes compared to Light microscopes?
Electron microscopes have a higher resolution and a higher magnification than light microscopes.
Conversion rates
nm –> um –> mm –> m –> km
Each increase is multiplying it by 1000.
What is a specialised cell?
A cell that is made for a certain specific function, it is developed in an organism over many years of evolution.
How are sperm cells adapted?
Half the chromosomes so in fusion the embryo has 46 chromosomes. They have lots of mitochondria to move quickly.
Acid in head so it can break down the walls of the egg.
Has a flagellum (tail).
How is a nerve cell adapted?
Nerve cells have a myelin sheath which acts as insulation so impulses travel faster. Lots of branches so can connect to lots of other nerve cells. Dendrites with protein receptors.
How is a muscle cell adapted?
Muscle cells have lots of mitochondria for contracting and moving the bones.
How is a root hair cell adapted?
Root hair cells have lots of mitochondria for active transport, large surface area due to the shape for high absorbtion rate.
How is the xylem adapted?
The xylem is made up of dead cells so that they don’t absorb any water. They don’t have walls to form a hollow tube for the water.
How is the phloem adapted?
They have sieve plates which are holes in the end of cell walls forming tubes the sugar and amino acids to get through.
What is diffusion?
The net movement of particles from a high to low concentration
Give examples of diffusion
Oxygen and carbon dioxide between the cells and blood.
Urea from cells to the plasma in the kidneys in excretion.
What 3 factors affect the rate of diffusion?
Difference in concentration (concentration gradient)
The temperature
The surface area
What is osmosis?
The net movement of water particles from a dilute to concentrated solution through a partially permeable membrane.
What will happen if the concentration outside a cell is higher than inside?
If the concentration outside is higher then the water will leave the cell causing the cell to shrivel.
What will happen if the concentration inside a cell is higher than the outside?
If the concentration inside is higher than the water will come into the cell causing it to swell.
What is active transport?
The net movement of particles from a low to high concentration through the use of energy.
Give an example of active transport
In root hair cells active transport is used to move mineral ions from the soil into the cell.
In the small intestine, active transport is used to move sugar into the blood.
Why can a single celled organism transport molecules in and out of itself easily?
It has a high surface area to volume ratio.
Why do multicellular organism have difficulty exchanging with the environment?
They have small surface area to volume ratios. This means they need specialised systems to obtain the molecules they need to survive.
How are exchange surface areas adapted for exchanging materials?
They’re thin - so substances only have a short distance to diffuse
They have a large surface area - so lots of a substance can diffuse at once
They maintain a concentration gradient (e.g. by having a good blood supply) - so that substances keep diffusing in the right direction.
They are often moist.
