Biology Paper 1
B1: Key Concepts
Microscopes,
cells, enzymes, osmosis, diffusion
B5: Health and Disease
B3: Genetics
B2: Cells and Growth
B4: Evolution
Mitosis, specialised cells, stem cells, nervous system
Meiosis, DNA, inheritance, variation
Classification, human evolution, natural selection and adaptions, selective breeding, genetic engineering
Non communicable, communicable, barriers, immune system, vaccination, antibiotics and new drugs.
B1: Microscopes
Questions
Give two types of electron microscope?
Explain why some cell structures can be seen with an electron microscope but not with a light microscope.
How do you calculate total magnification?
What does resolution mean?
Describe how you can estimate sizes using microscopes field of view.
What to the prefixes milli-, micro-, nano- and pico- mean?
How do you calculate specimen sizes?
Electron microscopes use a beam of electrons to view an image.
Resoulution: the ability to distinguish between two points is higher with the electron microscope. - the smallest distance between two points that can still be seen.
Calculating magnification
Magnification is how much bigger a sample appears to be under the microscope than it is in real life.
To calculate magnification:
Use the scale bar to get real size
Measure diameter with ruler to get image size in millimetres
Convert image size to same units as real size - micrometers
Image size ÷ real size = magnification
Remember units of magnification is ‘x’ before the number
B1: Cells
Questions
Can you list all the parts of plant and animal cells?
Can you describe the function of all of the parts of plant and animal cells?
Can you describe the functions of common parts of bacteria?
Can you describe how sperm cells are adapted to their function?
Can you describe how eggs cells are adapted to their function?
Can you describe how ciliated epithelial cells are adapted to their function?
What is the difference between cilia and villi?
Animal Cell
Plant Cell
Eukaryotic and Prokaryotic Cells
Eukaroyotic cells have genetic material is enclosed in a nucleus.
Prokaryotic cells are much smaller in comparison and the genetic material is not enclosed in a nucleus.
Egg and Sperm Cell
Any cells that have a nucleus is described as eukaryotic
B1: Enzymes
Questions
What are enzymes?
How do they work?
Why are they important?
Give an example of enzymes and where they are found in the human in the human body
Explain why enzymes have a particular shape
Describe how the following factors affect enzyme action: temperature, substrate concentration, and pH.
Explain how enzymes can become denatured.
Enzymes are biological catalysts and work via the lock and key theory.
Enzymes are proteins. The amino acids chains are folded to form the active site.
The chain folding depends on the base sequence of the protein molecules.
The substrate binds to the active site and the reactions are catalysed by enzyme.
Digestive Enzymes
In most animals digestion happens inside. But bacteria secrete enzymes to digest food outside of the cells, and then absorb the digestived molecules.
Digestion - breakdown of polymers to monomers.
Synthesis - build up of monomers to polymers.
Digestion and synthesis happen slowly so your body needs enzymes to speed it up.
In the pancreas there are many cells with many ribosomes to make enzymes
Types of Enzymes
Amylase
Lipase
Protease
Enzymes are proteins that act as biological catalysts, meaning they speed up reactions without being used up.
Substrate - Protein
Product - amino acids
Substrate - fat (lipids)
Product - fatty acids
Substrate - startch
simple sugars, glucose
An enzyme works on a molecule known as the substrate, and the molecules formed by the reaction are the products.
Due to an enzyme’s active site and its substrate being complementary in shape, an enzyme will only work on one substrate.
It is substrate specific. When enzymes and substrates collide they form an enyzme substrate complex. It is within this complex that the reaction takes place and the product is released, leaving the enzyme free to act again.
This theroy of enzyme action is known as the lock and key model.
Factors affecting enzymes activity
Temperature
Enzyme concentration
pH
The higher the enzyme concentration, the more enzymes there are to form enzyme-substrate complexes, leading to an increase in enzyme activity.
As temperature increases to the optimum, the kinetic energy of the enzyme and substrate increases, causing more collisions between the enzyme and substrate.
Deviating from the optimum pH (too high or too low) causes the enzyme’s active site to become denatured and the active site loses its important shape.
It can no longer form enzyme-substrate complexes, leading to a decrease in enzyme activity.
This causes the formation of more enzyme - substrate complexes, leading to an increase in enzyme activity. As the temperature increase over the optimum temperature the enzyme's active site becomes denatured.
Enzyme Practical
Effect of temperature on the action of an enzyme
click to edit
set up water baths at various temperatures (e.g. 0°C, 20°C, 40°C, 60°C and 80°C).
Add starch solution to 5 test tubes.
Add amylase solution to another 5 test tubes.
Place one starch and one amylase test tube into each water bath for 5 minutes - to allow the enzyme and substrate to reach the desired temperature.
Place 1 drop of iodine into each dimple on a spotting tile.
Add the amylase to the starch in the 0°C water bath.
Start the timer.
Every minute remove a sample of the starch-amylase solution and add it to a drop of iodine on the spotting tile.
Repeat step 8 until the iodine no longer changes colour - meaning that there is no starch present, in other words the amylase has broken all starch down.
Repeat steps 6-9 for each of the temperatures.
Record results.
B1 : Specialsied cells
A specialised cells is a cell that has adadpted to carry out a specific function.
All human cells have the same basic design, but are adapted to perform different functions.
Adaptions and Functions
What adaptions would a cell involved in digestion need?
How would it differ to one invloved in reproduction?
Egg Cell
What are its functions?
The main function of egg cell is to join with the male cell (sperm cell) for the purpose of reproduction. They also provide foodfor new cells thatare made in the process.
Sperm Cell
What are it's functions?
The main function of the cell is just like the main purpose of the egg cell, for the purpose or reproduction.
Ciliated epithermal cells
What are it's functions?
Ciliated epithelium is a thin tissue that has hair-like structures on it. These hairs, called cilia, move back and forth to help move particles out of our body.