Paper 1 overview

Created by

annabelle h

Cards (112)

What types of cells can be observed with a light microscope?
Cells and their nuclei
What advantage does an electron microscope have over a light microscope?
It allows us to see finer details of organelles
How can you calculate the actual size of a cell using a microscope?
image size divided by magnification
What are the two main groups of cells?
Eukaryotic and prokaryotic cells
What is a characteristic of eukaryotic cells?
They have a nucleus containing DNA
Where is DNA found in prokaryotic cells?
In a ring called a plasmid
What is the function of the cell membrane?
It keeps everything inside the cell and is semi-permeable
What additional structure do plant cells and most bacteria have?
An extra cell wall made of cellulose
What is the cytoplasm?
The liquid that makes up the cell where most chemical reactions occur
Where does respiration take place in a cell?
In the mitochondria
What is the role of ribosomes in a cell?
They assemble or synthesize proteins
What do chloroplasts contain and what is their function?
They contain chlorophyll and are where photosynthesis takes place
What is a permanent vacuole in plant cells used for?
To store sap
How do bacteria multiply?
By binary fission
What is the procedure for culturing bacteria on agar using aseptic technique?
Lift the lid of the dish towards a flame to move microbes away
Use sterilized equipment to place bacteria culture on agar
Tape the lid partially to allow air in
Incubate at 25°C
What is the chromosome number in human diploid cells?
46 chromosomes (23 pairs)
What are gametes and how many chromosomes do they have?
Gametes have 23 chromosomes, which is half of the diploid number
What is the process of mitosis?
The duplication of genetic material and division into two identical cells
What are stem cells?
Cells that haven't yet specialized
Where are stem cells found in humans and animals?
In embryos and bone marrow
How can stem cells be used in medicine?
To combat conditions like diabetes and paralysis
What is diffusion?
the movement of particles from an area o high concentration to an area of low concentration against a concentration gradient
What is osmosis?
The diffusion of water molecules from an area of high concentration to an area of low concentration across a partially permeable membrane
How can the rate of diffusion be increased?
By increasing concentration difference, temperature, or surface area
What is the practical procedure for investigating osmosis using potato cylinders?
Cut equal size potato cylinders and weigh them
Place in test tubes with varying sugar concentrations
After a day, remove and weigh again
Calculate percentage change in mass
Plot results against sugar concentration
What is active transport?
The movement of substances from a low concentration to a high concentration through a semi permeable membrane
What is a tissue?
A group of similar cells working together
What is an organ?
A structure made of different tissues working together
What is an organ system?
A group of organs working together
What is the function of bile?
To neutralize stomach acid and emulsify fats
What are enzymes?
Biological catalysts that speed up chemical reactions
What does amylase do?
It breaks down starch into glucose
What is the lock and key principle in enzyme activity?
Enzymes are specific and only work with substrates that fit their active site
What happens to an enzyme at its optimum temperature?
The rate of enzyme activity is maximized
What is denaturation in enzymes?
When the active site changes shape and the substrate can no longer bind
What is the practical procedure for investigating enzyme activity with amylase and starch?
Mix amylase with starch at different temperatures or pH levels
Remove drops every 10 seconds and test with iodine
Record the time taken for starch to be broken down
Plot results against temperature or pH
What color does iodine turn in the presence of starch?
blue/black
What color does Benedict's solution turn in the presence of sugars?
From blue to orange
What color does Biuret's reagent turn in the presence of proteins?
From blue to purple
What happens to cold ethanol in the presence of lipids?
It turns cloudy