B1 Flashcards
What does the nucleus do?
Controls activities of the cell
Contains organism’s genetic material
Determines cell’s appearance and function
Contains instructions to make new cells or organisms
What does the mitochondria do?
Where respiration happens
Enzymes enable glucose and oxygen to react together to transfer viral energy to the organism
What is the cell membrane?
A barrier that controls which substances enter and leave the cell
What is the cell wall?
It surrounds the cell and is made of cellulose
Makes the wall rigid and supports the cell
What is the chloroplast?
Contains green chlorophyll
This transfers energy from the sun to the plant which is used in photosynthesis
Chloroplasts are only in the green parts of the cell
What is the vacuole?
Full of cell sap
Water solution of sugar and salts
Helps keep the cell rigid
Supports the plant and keeping it upright
What does an animal cell contain?
Nucleus
Mitochondria
Cytoplasm
Cell membrane
What does a plant cell contain?
Everything is an animal cell as well as
Vacuole
Cell wall
Chloroplasts
What does a prokaryotic cell contain?
Cell wall
Genetic material
Cytoplasm
Cell membrane
A bacterial chromosome which is usually circular
What features do bacterial cells contain?
Flagella
Pili
Slime capsule
Plasmid
What is the flagella and what does it do?
‘Tail-like’ structures that allow the cell to move through liquids
What are pili and what do they do?
Tiny ‘hairlike’ structures that enable the cell to attach to structures
Also used to transfer genetic material between bacteria.
What is the slime capsule and what does it do?
Layer outside the cell wall
Protects bacterium from drying out and from poisonous substances
Helps bacteria stick to smooth substances
What is a plasmid and what does it do?
A circular piece of DNA that is used to store extra genes
Those genes are not needed for the bacterium’s survival but may help in times of stress
As an example, this is where antibiotic resistance genes are normally found
What is the equation for total magnification?
Eyepiece lens magnification x objective lens magnification
What is used to identify the nucleus of an animal cell?
Methylene blue
What is used to identify the nucleus of a plant cell?
Iodine solution
What is used to identify bacterial wall cells?
Crystal violet and it stains them
What does a light microscope contain?
Eyepiece lens
Objective lens
Coarse focus
Fine focus
Stage
Slide
Light/mirror
What are the two types of electron microscopy?
Transmission electron microscopes (TEM)
Scanning electron microscope (SEM)
What does a TEM do?
Produce the most magnified image
Uses a beam of electrons to pass through a thin slice of the sample producing a 2D image
What does an SEM do?
Produces a 3D imagine of a surface
They send a beam of electrons across the surface of a specimen. The reflected electrons are collected to produce an image
What does an electron microscope contain from top to bottom?
Electron source
Electron beam
Specimen
Electromagnetic lenses
Viewing screen
What are the advantages and disadvantages of a light microscope?
Cheap to buy and operate
Small and portable
Simpler to prepare a sample
Natural colour is seen (unless staining is used)
Specimens can be alive or dead
What are the advantages and disadvantages of an electron microscope?
Expensive to buy and operate
Large and more difficult to move
Sample preparation is complex
Black and white images produced
Specimens have to be dead
Better magnification that an electron microscope
What is a chromosome?
A molecule of DNA
How many chromosomes do most people have in each of their cells?
46
What are genes?
DNA is arranged into sections; SHORT SECTIONS OF DNA THAT CODE FOR A CHARACTERISTIC , such as eye colour are called genes.
What do genes determine?
Blood group
Whether you have freckles or dimples
And more
What does a DNA molecule look like?
And circular phosphate bonded to a triangular deoxy-ribose sugar bonded to a rectangular base
What are the bases?
Adenine
Thymine
Guanine
Cytosine
What bases bond with what?
Adenine to Thymine
Guanine to Cytosine
What is transcription?
The DNA around a gene unzips so that strands are separated and one of these strands act as a template. Complimentary bases attache to the strand being copied which forms mRNA. There is no Thymine so Uracil is used instead.
How are proteins made?
By a process called translation
What is translation?
The mRNA made from transcription attaches to a ribosome. Here, the nucleotide is interpreted and a new protein is made:
- The ribosome ‘reads’ the nucleotides on the mRNA in groups of three (base triplets or codons and each triplet codes for a specific amino acid)
- The ribosome continues to read the triplet code, adding more and more amino acids.
- The amino acids join together in a chain and that is called a protein.
What is an enzyme?
A protein that is also a biological catalyst
What do enzymes look like?
The are long chains of amino acids that are folded together to form a specific shape
Do enzymes bind to all molecules?
No as they are highly specific with their enzyme substrate complex
What is the lock and key hypothesis?
An enzyme is like a lock and a substrate is like a key and only a certain key can fit the lock meaning only a certain substrate can bind with a a certain enzyme
What factors affect enzymes?
Temperature and pH and the concentrations of the enzyme and substrate
What are the best conditions called for an enzyme?
Optimum conditions
How do enzymes become denatured?
If the temperature is too hot
What enzyme breaks down protein?
Protease
What enzyme breaks down lipids?
Lipase
What enzymes breaks down carbohydrates?
Carbohydrase
What is the word equation for aerobic respiration?
Glucose + oxygen — carbon dioxide + water
What is the symbol equation for aerobic respiration?
C6H12O6 + 6O2 — 6CO2+ 6H20
What is aerobic respiration?
Respiration that uses oxygen
What is the word equation for anaerobic respiration in plant?
Glucose - Ethanol + Carbon Dioxide
What is the symbol equation for anaerobic respiration?
C6H12O6 — 2C5H5OH + 2CO2
What is the equation for anaerobic respiration in humans?
Glucose — lactic acid
What are the downsides of anaerobic respiration?
Lactic acid build up in your muscles, which causes pain and stops the muscles from contracting (fatigue)
Why do you breath heavily after exercising?
To get extra oxygen to react with the lactic acid and break it down and the oxygen needed for this process is called the oxygen debt.
What is the equation for the rate of photosynthesis?
1/time
Where does photosynthesis occur?
Inside the plant’s chloroplast as they contain chlorophyll
What is the word equation for photosynthesis?
Carbon dioxide + water — glucose + oxygen
What is the symbol equation for photosynthesis?
6CO2 + 6H20 — C6H120 + 602
What is the law for relative light intensity?
The inverse square law
What is the formula for relative light intensity?
1/(distance from light source)^2
How does light intensity affect the rate of photosynthesis?
The higher the light intensity the faster the rate of photosynthesis until photosynthesis reaches its maximum rate
How does carbon dioxide affect the rate of photosynthesis?
The greater the carbon dioxide concentration, the faster the rate if reaction
Why is carbon dioxide the most common limiting factor of photosynthesis?
The atmosphere only contains about 0.04% carbon dioxide
Why do farmers use greenhouses?
To artificially increase the level of CO2 which increases photosynthesis.
How does temperature affect the rate of photosynthesis?
The higher the temperature, the higher the rate of photosynthesis untilthe temperature increases too high and the enzymes denature
What factors can we change to see their effect on the rate of photosynthesis?
Light intensity (place light sources at different distances)
CO2 concentration (add potassium hydrogen carbonate to the water)
Temperature (place apparatus in water baths at different temperature)
