Topic 1 - Key Concepts in Biology Flashcards
What are all living things made up of?
Cells
What are the two types of cell?
- Eukaryotic (Complex, animal and plant cells)
- Prokaryotic (Simple, bacteria)
What is a prokaryote?
A single-celled organism
What do both animal and plant cells contain?
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
- Ribosomes
What extra subcellular structures do plant cells contain?
- Cell wall
- Vacuole
- Chloroplasts
What is the main structure that a bacterial cell does not contain?
Nucleus
What is a specialised cell?
A cell with a specialised purpose
Name three specialised cells, and give reasoning:
- Sperm Cell: Many mitochondria to swim, enzyme in head, has a flagellum
- Egg Cell: Nutrients in cytoplasm
- Ciliated Epithelial Cell: Have cilia on the ends
What apparatus do we use to study cells?
Microscopes
What is the most powerful microscope, and what is its magnification power?
Electron microscope - 2000000x
What is the equation for total magnification?
Total magnification = Eyepiece lens magnification x Objective lens magnification
What is the equation for magnification if you don’t know the lens magnifications?
Magnification = Image size / Real size
What is an enzyme?
A catalyst produced by living things
Why does an enzyme only catalyse one reaction?
Because the active site is of a shape that only fits a particular substrate
What 3 factors affect enzyme-catalysed rates of reaction, and why?
- Temperature: High temp. causes denaturing
- pH: Low and high pH cause enzymes to denature
- Substrate conc.: More substrates means more active sites are filled
What break down big molecules such as carbohydrates, proteins and lipids?
Catalysts
Name the three conversions of big molecules, including the enzyme used:
Starch + Amylase = Maltose
Protein + Protease = Amino Acids
Lipid + Lipase = Glycerol and fatty acids
What is the test for sugars?
- Add Benedict’s reagent (blue) to a sample
- Heat to 75 degrees Celsius
- If the test is positive, a precipitate either yellow, orange or red in colour will form
What is the test for starch?
- Add iodine to the test sample
- If the test is positive, the sample changes from browny-orange to blue-black.
What is the test for lipids?
- Add ethanol to the test substance and shake
- When it dissolves, add it to water
- If the test is positive, a milky coloured precipitate will rise above the water
What is the test for proteins?
- Add potassium hydroxide to the solution
- Add copper II sulfate (blue)
- If the test is positive, the colour will change from blue to purple
How do you test the number of calories in a food?
Calorimetry
What are the steps for carrying out a calorimetry?
- Weigh the sample
- Measure a set volume of water
- Measure the temperature
- Heat the sample until it burns
- Hold the burning food under the water
- Measure the change in temperature
How do you calculate the energy in food (J)?
Energy in food = Mass of water x Temperature change x 4.2