What is a eukaryotes?
Have a cytoplasm, cell membrane and have their genetic material contained within a nucleus
Name examples of eukaryotic cells
Animal
Plant
Fungal
Protests
What is a prokaryote
Have a cytoplasm and cell membrane surrounded by cell wall and do not have their genetic material contained within a nucleus
Name examples or prokaryotic cells
Bacteria
What is bacteria DNA like
It is a single DNA loop and there may be small rings of DNA called plasmids
What does and animal cell contain?
Nucleus Cytoplasm Mitochondria Ribosomes Cell membrane- semi permeable
What does a plant cell have that an animal doesn’t
Vacuole- contains cell sap
Chloroplasts that contain the pigment chlorophyll
Cell wall made of cellulose
How big are animal cells
10micrometers - 30
How big are plant cells
10 micrometers- 100
How does bacteria divide
Binary fission
How is a root hair cell specialised
Large surface area
Many mitochondria for active transport
No chloroplast as it is not needed as they are underground
Large vacuole
What is a root hair cells purpose?
To absorb water and minerals from soil
How is a muscle cell specialised
Proteins help the fibres slide
Extra mitochondria to transfer energy for contractions
How is a nerve cell specialised
Myelin sheath to insulate impulse
Dendrites to connect to others
Long axon
How is a sperm cell specialised
Contains half DNA
Tail to swim
Extra mitochondria to provide energy for tail
Acrosome to break egg
How is a phloem specialised and what is its purposes?
It has companion cells
Seive plates so sugars can flow easy by
Translocation
To transport oxygen and glucose from leaves
How is xylem cell specialised and what is its purpose?
Made from dead cells
Strengthened by lignin hollow tube
What are the advantages of using an electron microscope instead of light?
Higher magnification
Higher resolution
What are the disadvantages of a light microscope
Limited magnification
Low resolution
Advantages of electron microscope?
High magnification
High resolution
What is the formula for image size?
Actual x magnification
Formula for magnification
Image / actual
How do you work out the clear zone when culturing microorganisms?
Pi r squared
How do you practise sterile technique
Use sterile petroleum dishes
Inoculation loops sterilised by flame
Tape lid shut
Why is it important that schools do the experiment under 25 degrees
Over this allows dangerous bacteria to grow
What are sub cellular structures
Structures inside a cell e.g. Nucleus
What does a nucleus do
Controls the activities of the cell and contains genetic material
What does a cytoplasm do
Where most of the chemical reactions take place
What does a cell membrane do
Controls the passage of substance in and out the cell
What does a mitochondria do
Where aerobic respiration takes place
What happens in ribosomes
Proteins are synthesised (made)
What is the job of chloroplast
Absorb light for photosynthesis
What is a cell wall
Made of cellulose and strengthens the cell
What is the purpose tor the vacuole
Supports the cell and makes it turgid. It is filled with cell sap
Why don’t all plant cells contain chloroplasts?
Because sometimes they are not needed e.g. Root hair cells don’t have them because they don’t receive any light
Which sub cellular structures controls the activities inside the cell?
Nucleus
Where are proteins made in a cell
Ribosomes
Three structures that are found in a plant cells but not in animal cells
Cell wall
Vacuole
Chloroplasts
What is the function of cell sap
Make the cell turgid and give support
Where is DNA found in a bacterium
Not in a nucleus but found as on looped chromosome in the cytoplasm
When were an electron microscope first used
1933
Why do you add stain when using a light microscope
To see all parts of the cell
What type of reproduction in binary fission
Asexual
What can bacteria be grown on
Nutrient brother solution
Or
Agar jelly
How fast can bacteria divide at optimum temperature
Once every 20 minutes
Arrange theses in order of size Bacterium Liver cell Nucleus Ribosomes Largest first
Liver cell
Nucleus
Bacterium
Ribosomes
How many micrometers is 0.005mm
5
What does a nucleus contain?
Chromosomes made of DNA molecules
What does each chromosome carry
A large number of genes
What are chromosomes found in
Pairs
What is the series of stages in which cells divide called
The cell cycle
What happens during the whole cell cycle
The genetic material is doubled and then divided into two identical cells
What must a cell do before it can divide
It needs to grow and increase the number of sub cellular structures such as ribosomes and mitochondria
What happens to the DNA before cell division
DNA replicates to form two copies of each chromosome
What happens during mitosis
One set of chromosomes is pulled to each end of the cell and the nucleus divides
What happens finally during cell division
The cytoplasm and cell membranes divide to form two identical cells
Why is cell division by mitosis important for multicellular organisms
Growth and development
What is the definition of a stem cell
An undifferentiated cell o an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation
How can human embryo stem cell be used
Can be cloned and made to differentiate into most different types of human cells
How can stem cells form adult bone marrow be used?
Can form many types of cells including blood cells
What can meristem tissue in plants differentiate into?
Any type of plant cell, throughout the life of the plant
How can stem cells be used for treatment ?
Help conditions such as diabetes and paralysis
What happens in therapeutic cloning?
An embryo is produced with the same genes as the patient . Stem cells from the embryo are not rejected by the patients body so they may be used for medical treatment
What are the risks of the use of stem cells?
Transfer viral infection
Some people have ethical or religious objections
What can meristems in plants be used for
Produce clones of plants quickly and economically
What are the advantages of using meristems?
Rare species I plants can be cloned to protect from extinction
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers
Complete the sentence
Substance may move into and out of cells across the cell membranes via ______________
Diffusion
What is the definition of diffusion?
Diffusion is the spreading out of the particles of any substance in solution, or particles of gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
Give two examples of substances transported in and out by diffusion in gas exchange
Oxygen and carbon dioxide
Give an example of diffusion that occurs when disposing of waste
Waste product from cells into the blood plasma for excretion in the kidney
What factors affect the rate of diffusion
Concentration gradient
The temperature
Surface area of the membrane
Does a single called organism have a relatively large surface area to volume ratio
Yes
What does a large surface area to volume ration give the single-called organism
Allows sufficient transport of molecules into and out of the cell to meet the needs of the organism
The effectiveness of an exchange surface is increased by
Having a large surface area
A membrane that is thin, to provide a short diffusion path
Having an efficient blood supply (in animals)
Being ventilated ( in animals, for gaseous exchange)
Complete the sentence
Water may move across cell membrane via ____________
Osmosis
What is osmosis?
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
What is active transport?
Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.
How does active transport help a root hair cell?
Active transport allows mineral ions to be absorbed into plant root hair from very dilute solutions in the soil.
Why do plants require ions?
For healthy growth
How does active transport help in the body?
It allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration.
What are sugar molecules used for in the body?
Cell respiration
A person opens a bottle of perfume. Why do people in the room smell it faster on a warm day?
Temperature affects the rate of diffusion. The higher the temperature the faster the particles move.
What is required for substances to be absorbed against a concentration gradient?
Energy from respiration
What are chromosomes made of
DNA
Name 2 sub cellular structures that increase in number before the cell divides
Ribosomes
Mitochondria
What is the proper name for copying DNA to form two copies of each chromosome
Replication
What are the two stages that are involved in the division of the genetic material
Division of the nucleus
Replicated chromosomes split at each pole
Name 2 structures that divide in the division into 2 cells
Cytoplasm
Cell membrane
Why is cell division by mitosis important?
Growth
Maintenance
Repair of multi cellular organisms
Development
Where can stem cells be obtained from to be cloned and become many types of human cells?
Embryo
Where can stem cells be obtained from to form blood cells in humans
Bone marrow
What type of tissues in plants can become any type of plant cell, throughout the life of the plant?
Meristem
Why is the production of clones using these tissues beneficial?
Reproduce quickly and cheaply/economical
Able to reproduce rare species and make plants that are desirable for farmers
Why are stem cells from an embryo useful in medical treatment?
Can treat diseases such as diabetes and paralysis
Won’t be rejected by patient
Give one risk of using stem cells for medical treatment
Viral infection
Why is cloning of rare species of benefit ?
Able to reproduce rare species identically, so they won’t become extinct.
Give one characteristic that plants may have that could be desirable for farmers, and therefore result in cloning of plants with this characteristic
Resistance to disease
What is the real name for the clear areas on a Petrie dish called
Inhibition zones
Describe how to draw a cell seen with a microscope correctly
Use a pencil
Draw clear lines, no sketches
Draw a scale
Label
How many micrometers in 1cm
10,000
The specification names 5 exchange surfaces in plants and animals that are adapted for exchanging materials. You need to know HOW they are adapted. What are they?
Leaves Lungs Small intestine Fish gills Root hair cell
What are the 4 features that increase the effectiveness of an exchange surface in multicellular organisms
Ventilation
Lots of blood supplied
Large surface area
Short diffusion distance
Where and how is active transport important in plants?
Minerals are needed to move from a low concentration in the soil to a high concentration in roots. They are needed for healthy growth
Give two differences between diffusion and active transport
Diffusion- high to low
Active transport- low to high
Active transport requires energy but diffusion is passive
Give 2 similarities between diffusion and osmosis
Neither require energy
Both go down concentration gradient
What is a micrometer
100
