2022 AS Paper 1 Flashcards
(16 cards)
Describe the mechanism for the absorption of amino acids in the ileum
- facilitated diffusion of amino acid into the cell
- sodium ions are actively transported from cell to blood
- this creates a sodium ion concentration gradient
- facilitated diffusion of amino acids into the blood
Give the two types of molecule from which a ribosome is made
- RNA
- Protein
Give 4 structural differences between DNA and mRNA
- DNA has deoxyribose, mRNA has ribose
- DNA has thymine, mRNA has uracil
- DNA is double stranded, mRNA is single stranded
- DNA has hydrogen bonds, mRNA does not
Describe and explain 1 difference between SEM and TEM
- SEM is 3D, TEM is 2D
- since electrons are deflected in SEM
Why is the resolution of an electron microscope higher than optical microscope
electron microscope has shorter wavelengths between its electrons
How to determine size of a structure using a microscope
- measure length of structure and divide by image length of scale bar
- multiply by actual length of scale bar
Name 2 structures found in all bacteria that aren’t found in plants
- circular DNA
- smaller ribosomes
Name 2 features of HIV particles that aren’t found in bacteria
- reverse transcriptase
- capsid
What can you conclude about the uptake of oxygen over the entire body of the lugworm
- oxygen enters via diffusion down a concentration gradient
- more oxygen is present where there are gills
- this is because gills increase SA to volume ratio
Describe how monomers join to form the primary structure of a protein
condensation reaction between amino acids, forming peptide bonds, forming a sequence of amino acids
1 similarity and 1 difference between induced fit model and lock and key theory
- both have a substrate which binds to active site
- induced fit changes shape for substrate to become complementary but lock and key doesn’t change shape
State how enzymes help reactions to proceed quickly at lower temperatures
lower activation energy
Explain a property of iron ions that enables these ions to carry out their role in red blood cells
contain haemoglobin so transport oxygen
What is a tumour
abnormal cells which undergo uncontrolled mitosis
Describe how to determine a reliable mitotic index from tissue observed using an optical microscope
count the cells undergoing mitosis in your field of view, divide by total number of cells in field of view, repeat many times
Suggest why the number of E.coli cells per mm3 in each culture after 24 hours might be lower if the student hadn’t used a sterilised pipette
other bacteria may have been introduced and these produce toxins
