biology paper 1 Flashcards
whats the diffrence between eukaryotes and prokaryotes?
2 marks
- eukaryotes are made from complex eukaryotic cells for things like animals and olants
- prokaryotes is a single prokaryotic cell made for things like bacteria
what do bacteria cells contain?
5 marks
- chromosomal DNA (in cytoplasm cuz no nucleus)
- ribosmes
- cell membrane
- Plasmid DNA - small loops od extra DNA
- Flagellum -> hair structure the rotates to move it
what is the diffrence between haploid and diploid?
1 marks
haploid have half the number of chromosomes as a diploid cell
explain how the egg and sperm are specialised for there funtion.
6 marks
EGG:
- nutrients in cytoplasm
- haploid nucleus
- after fertilisation, the membrane changes structure to block sperm
SPERM:
- long tail to swim
- lots of mitochondria for energy
- acrosome at front stores enzymes to get though eggs membrane
- haploid nucleus
how are ciliated epithelial cells specialised?
3 marks
- line the surface of organ
- cilla on surface
- that moves substances in one direction along the surface
- e.g lining of air ways have them to move mucus away from lungs
What is the difference between a light and an electron microscope?
4 marks
light 1590:
- Work by passing light through the specimen
- They let us see cellular structures.
electron 1930:
- They use electrons that can have a very high magnification and resolution
- They let us see internal structures of subcellular structures.
practical
How would you view a specsman using a light microscope?
6 marks
- Take a thin slice of your specimen and put it on a clean slide
- Use a pipette to put a drop of water in the middle to secure it
- If specimen is colours or transparent, drop a stain on it (iodine)
- Gently press down cover slip on so there are no air bubbles trapped under it. Then clip it to the stage.
- Select the lowest objective lens And used the adjustment knob to move the stage up so The specimen is in close focus.
- Then adjust the focus with the fine adjustment knob until you get a clear image.
- If you need greater magnification, switch to a higher objective lens and refocus
- Position of ruler at the stage and use it to measure the diameter of the area visible To work out the magnification
How would you work out total magnification
1 mark
eyepiece lens mag x objective lens mag
practical
How can you investigate the effect of pH on enzyme activity?
6 marks
- Put a drop of iodine into every hole of a spotting tile
- Place a bonson burner on a heap proof mat and tripod and gauze
- Put beaker of water on top tripod and heat until thirty five degrees measured using a thermometer
- Use syringe to Add 3cm^3 of amylase solution. one centimetres cubed of buffer solution with a pH of 5 using measuring cylinders and put in the beaker and wait 5mins
- Use a different syringe to add 3cm^3 of starch solution to a boiling tube
- Immediately mix the contents of the boiling tube and start a stopwatch
- Use continuous sampling to record how long it takes for the amylase breakdown all of the starch By sampling it in an iodine solution untill it remains browny orange.
- Repeat experiment with different ph values and make sure. and make sure to continue any control variables
how do you calculate rate of reaction for the enzyme practicalif you dont know the amount of change?
1 mark
1000/time
otherwise change / time
Why do plants and animals have enzymes?
2 marks
- Many molecules in the food we eat are too big So. Digestive enzymes break them down into smaller soluble molecules that can pass through its digestive system
- Plant store starch, which needs to be broken down into glucose to respire So enzymes need to break them down.
what enzyme breaks down:
- Carbohydrates (starch)
- Proteins
- Lipids
3 marks
and what do they turn to
- amylase turn it it sugar e.g (glucose)
- protease converts it to amino acids
- lipase turns it to fatty acids and glycerol
practical:
How can you test for sugar?
3 marks
- Add Benedict’s reagent (blue) to a sample and heat the water to 75 degrees.
- If it’s positive it will form a Coloured precipitate.
- The higher the concentration, the further the colour change.e.g the highest is brick red
How can you test for starch?
- Add iodine
- Is starches present it will go from browny-orange to blue black
- otherwise it will stay browny-orange
How do you test for lipids?
4 marks
- Shake the substance with ethanol for about a minute until it dissolves.
- then Pour water
- If lipids are present a precipitate will form showing up as a Milky colour
- The more lipids, the more noticeable
How do you test for proteins?
5 marks
- Biruret test
- Add a few drops of potassium hydroxide to make solution alkaline
- Add copper sulphate (blue)
- If proteins solution will go purple
- else it will stay blue
practical
How can you burn food to see how much energy it contains?
6 marks
calorimetry
- Weigh a small amount of the food then put it onto a mounted needle.
- Add a set volume of water to a boiling tube Held by a clamp
- Measure the temperature of the water, then set fire to the food using a bunsen burner flame. Make sure the bunsen burner isn’t near the water or is may mess it up
- Hold the burning food under the boiling tube until it goes out, then relight the food and hold it under the tube. Keep. doing this until it won’t set fire again.
- Measure the final temperature of the water
- mass of water x temp change x 4.2 (SHC of water) = energy in food
food must be flamable
practical
How do you investigate osmosis with diffrent concentrations using pattato?
7 marks
could be with any plant based thing and with pH / temp / conc
- Prepare a bunch of solutions with arranging water concentration
- Cut a potato into the Same sized pieces (1cm^2)
- Divide Pieces into groups of 3 and use a electronic balance for the mass of each group.
- Place one group into each solution
- Leave cylinders for about 40 minutes.
- Dry the pieces, to remove any excess water
- Weigh each group again and record your results
- Repeat experiment at different water concentrations
You also can say a more concentrated sucrose solution meaning a less concentrated water solution
What do you do with your results after a osmosis practical?
4 marks
- Work out percentage change
- ((final mass - inital mass)/inital mass) x100
- Plot a graph.
- Where percentage change hits the zero on the graph. That is the concentration of water in the plant
what happens in interphase?
3 marks
- DNA is spread out in long strings
- subcellular structures duplicate
- DNA is copied and forms X shaped chromosomes that is an exact duplicate of each other
what happens in mitosis?
8 marks
4 stages
- Prophase - chromosomes condense and the membrane around the nucleus breaks down, allowing the chromosomes to lie free in the cytoplasm
- metaphase - chromosomes lineup in the centre
- anaphase - spindle fibers pull chromosomes apart, then chromatids are pulled to opposite ends
- telophase - membranes form around each of the sets of chromosomes becoming nuclei
what is cytokines?
1 marks
- before the end of telophase, the cytoplasm and cell membrane divide to form separate cells.
what is the difference between cell differentiation, cell division and cell elongation?
3 marks
- cell differentiation -> A process where is cell becomes specialised
- cell division -> mitosis
- cell elongation -> where a plant cell expands making the cell bigger -> growing the plant
how is cancer caused?
3 marks
- if there is a mutation that causes a change in genes that controls cell division it may start dividing uncontrollably
- this can result in a mass of abnormal cells (tumour)
- if the tumour invades and destroys surrounding tissue, it’s called cancer