Studied by 2 peopleContains DNA to control the cell
What is the function of the nucleus?
Controls entry and exit of substances
What is the function of the cell membrane?
Provides structure and support
What is the function of the cell wall?
Carry out respiration to release energy
What is the function of mitochondria?
Protein synthesis
What is the function of ribosomes?
Carry out photosynthesis
What is the function of chloroplasts?
Contains cell sap
What is the function of a vacuole?
A cell that does not have a nucleus
Define a prokaryote
A cell that has DNA in a nucleus
Define a eukaryote
Nucleus, mitochondria, chloroplasts
Name two cell structures that are in a eukaryote but not in a prokaryote
A small loop of DNA in bacteria
What is a plasmid?
Cellulose
What is a plant cell wall made from?
As a single, free-floating loop; also on plasmids
How is DNA stored in a bacterial cell?
The process by which cells become specialised
What is differentiation?
Magnification = Image Size ÷ Actual Size
What is the equation for magnification?
0.0136mm, or 13.6µm
A photograph of a cell is 15mm long. It has a magnification of 1100x. What is the actual size?
5400µm, or 5.4mm
A cell is 12µm wide. It is magnified by 450 times. How big is the image?
6000 times
If the image of a virus is 1.2mm, and its actual size is 0.2µm, how much has it been magnified by?
38.5mm
Convert 38500µm into mm
1000
How many µm are in 1mm?
1.74 x 10^4 m
Write 17400m in standard form
3.4 x 10^-3
Write 0.0034 in standard form
It has a tail to swim to the egg
How is a sperm cell adapted for its function?
It has a long axon to conduct impulses over long distances
How is a nerve cell adapted for its function?
It can contract to cause movement
How is a muscle cell adapted for its function?
It has a large surface area to increase osmosis of water
How is a root hair cell adapted for its function?
It has hollow ends to transport water
How is a xylem cell adapted for its function?
It has sieve tubes to transport sugars
How is a phloem cell adapted for its function?
An undifferentiated cell that can differentiate to become any type of specialised cell
What is a stem cell?
In embryos and in bone marrow
Where are stem cells most commonly found in animals?
Plant tissue containing stem cells
What is meristem tissue?
Throughout the whole life of the plant
When are plant cells able to differentiate?
At an early stage of development (as an embryo)
When do most animal cells differentiate?
Resolution is the smallest distance between two separate points
What is the "resolution" of a microscope?
They have a higher resolution and higher magnification
Why are electron microscopes better than light microscopes?
Ribosomes
Give an example of an organelle you could see with an electron microscope, but not with a light microscope?
Double helix
What shape is DNA?
Chromosomes
What molecule is DNA stored as?
In pairs
How are chromosomes usually found in body cells?
A small section of DNA that codes for a specific protein
What is a gene?
Cell division
What is mitosis?
To grow and to replace cells
What are the two main purposes of mitosis?
It must replicate its DNA to form two copies of each chromosome
What must happen in a cell before mitosis can take place?
One set of chromosomes is pulled to each end of the cell and the nucleus divides
Once DNA has been replicated, what happens next in mitosis?
Two genetically identical daughter cells
What are the products of mitosis?
The stages in a cell as it grows and goes through mitosis
What is the cell cycle?
Diabetes and paralysis
What conditions may stem cells be able to help with?
From stem cells in bone marrow
How are most blood cells formed?
When an embryo is produced with the patient's genes so that stem cells from the embryo can be used
What is therapeutic cloning?
They contain the same genes as the patient, so are not rejected by the patient's body
Why are stem cells made by therapeutic cloning more useful for medical treatments?
For preventing the extinction of rare plant species, and for producing large numbers of identical disease-resistant crops
Give two ways using stem cells to clone plants may be useful
The movement of particles from a high concentration to a low concentration down a concentration gradient
Define diffusion
Temperature, surface area, difference in concentration
What factors affect the rate of diffusion?
There are lots of villi to give a large surface area, villi contain lots of capillaries close to the surface so there is a short diffusion distance
How is the small intestine adapted for diffusion?
Lots of alveoli give a large surface area, they have thin walls and capillaries are close so there is a short diffusion distance
How are the lungs adapted for diffusion?
Gills have lots of filaments to give a large surface area, there are lots of capillaries with a short distance for diffusion
How are fish gills adapted for diffusion?
Roots have lots of long root hair cells to give a large surface area for osmosis
How are plant roots adapted to absorb water?
Root hair cells have mitochondria to release energy for active transport of mineral ions
How are plant roots adapted to absorb mineral ions?
Leaves have lots of stomata on the underside to allow carbon dioxide to diffuse in
How are leaves adapted for gas exchange?
The movement of water from a high water potential to a low water potential across a partially permeable membrane
Define osmosis
(Change in mass ÷ Starting mass) x 100
How would you calculate % change in mass of a potato chip in sucrose solution?
To remove excess water, so it doesn't increase the mass
Why should you blot a potato chip dry before taking its mass?
So that you can compare different chips, as the starting mass of each potato may not be the same
Why do you calculate %change in mass of a potato chip rather than just change in mass?
The movement of particles from a low concentration to a high concentration against a concentration gradient, using energy
Define active transport
Absorption of mineral ions in root hair cells
Explain one example of active transport in plants
Absorption of glucose in the small intestine
Explain one example of active transport in animals
A group of cells with similar structure and function
Define a tissue
A group of tissues working together to perform a function
Define an organ
A group of organs working together
Deine an organ system
Epithelial tissue, muscle tissue, nerve tissue, glandular tissue
Give two examples of tissues in animals
Palisade tissue, spongy mesophyll tissue, xylem tissue, phloem tissue
Give two examples of tissues in plants
Heart, lungs, stomach, brain, liver
Give two examples of organs in animals
Leaf, root, stem, flower
Give two examples of organs in plants
A biological catalyst that carries out metabolic reactions in living organisms
Define an enzyme
A substance that is broken down by an enzyme
What is a substrate?
Active site
Where does a substrate bind to an enzyme?
Enzyme-substrate complex
What is formed when an enzyme binds to a substrate?
Each type of enzyme has an active site that only fits one specific substrate
Why are enzymes specific?
Protein
What are enzymes made of?
High temperatures or pH that is too high or low
What conditions cause enzymes to denature?
When an enzyme cannot work because its active site has lost its specific shape so the substrate no longer fits
Define denature
37oC
What is human body temperature?
A substrate is specific to one enzyme because of the specific shape of its active site (like a key fitting a lock)
What is the Lock and Key Theory?
To break large, insoluble molecules into small, soluble molecules so they can be absorbed
What is the purpose of digestion
Salivary glands and pancreas
Where is amylase made?
Stomach and small intestine
Where is protease made?
Pancreas and Small intestine
Where is lipase made?
Starch
What is the substrate of amylase?
Protein
What is the substrate of protease?
Lipids (fats)
What is the substrate of lipase?
Carbohydrate
What is the substrate of carbohydrase?
Glucose
What are the products of amylase digesting starch?
Amino acids
What are the products of protease digesting proteins?
Glycerol and fatty acids
What are the products of lipase digesting lipids?
Liver
Where is bile made?
Gall bladder
Where is bile stored?
To emulsify fats, and to neutralise stomach acid
Give two functions of bile
To break large fats into small droplets, to increase surface area for lipase
What is the purpose of emulsification
So that enzymes aren't denatured
Why must hydrochloric acid from the stomach be neutralised by bile in the small intestine?
Water bath
What equipment is used to control temperature in an investigation?
Note
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