Mock Paper 2 Flashcards
Evolution (11)
- evolution occurs when heritable characteristic of a species change
- speciation is the development of a new species from a pre-existing species over time
- variation is differences between organisms of the same species
- Causes of variation are meiosis, random fertilisation, and mutation
- overproduction - more young than will survive
- selective pressure - competition for resources
- variations - individuals vary from one another
- survival of the fittest phenotype - individuals with favoured characteristics will survive and pass on genes
- favourable characteristics increase
- reproductive isolation of separated population
- geographical isolation leads to speciation
Outline functions of RER and Golgi Apparatus
- ribosomes if RER produce proteins
- proteins from RER are for secretion outside cell
- Golgi modifies proteins
- Exocytosis of proteins in vesicles from the Golgi
Outline the control of metabolism by end-product inhibition
- metabolic pathway is a chain of enzyme-catalyzed reactions
- non-competitive inhibition
- negative feedback
- Changes shape of active site
- Inhibits first enzyme in pathway
Explain how hydrophobic and hydrophilic properties contribute to the arrangement of molecules in a membrane.
- phospholipid bilayer
- hydrophilic is attracted to what, hydrophobic is not
- hydrophilic head faces outwards
- hydrophobic tails face inwards
- cholesterol is amphipathic and located in phospholipids
- hydrophobic proteins in phospholipid bilayer
- hydrophilic proteins are on membrane surface - peripheral proteins
Outline the process of inhalation in humans
- diaphragm and external intercostal muscles contract
- as volumes increases, pressure decreases
- air enters lungs due to high atmospheric pressure
-diaphragm moves down
Describe the function of valves in mammalian hearts
- prevents backflow
- open valves allow blood to flow through
- closed semilunar valve allows ventricles to fill with blood
- AV valves prevent backflow from ventricle to atrium
explain how blood solute concentration are kept within narrow limits in the human body
- solute concentration is monitored by hypothalamus
- pituitary releases ADH
- ADH is released when solute concentration is too high
- Collecting duct becomes more permeable
- water is reabsorbed
- negative feedback
- small volume of urine produced with ADH
Outline the roles of helicase and ligase in DNA replication
- helicase unwinds DNA
- helicase breaks hydrogen bonds
-ligase joins Okazaki fragments - ligadles makes Covent bonds between nucleotides
Outline features of an ecosystem that makes them sustainable
- water supplied by rainfall
- sun provides energy
- decomposes break down organic matter
- recycling nutrients
Compare and contrast prokaryotes and mitochondria
- prokaryote has a cell wall, mitochondria does not
- prokaryotes is single membrane, mitochondria is double
- both have 70S ribosomes
- Both rod shaped
Histones
- Histones package the DNA into nucleosomes
- nucleosomes consists of a strand of DNA coiled around 8 histone proteins
- nucleosomes helps supercoil DNA
Outline 4 types of membrane transport, including their use of energy
- simple diffusion is passive movement if molecules along a concentration gradient
- facilitated diffusion is passive movement of molecules along a concentration gradient through protein channels
- osmosis is the passage of water through a membrane from a region of low solute concentration to a region of high solute concentration
- active transport is the movement of molecules against the concentration gradient through membrane pumps with the use of ATP
Draw the structure of a dipeptide
Check word
Explain the cause of sickle cell anaemia and how this disease affects humans
- caused by base substitution from GAG to GTG
- mRNA copies the mutation
- change in the shape of RBC
-blocks blood flow - sickles RBC can’t carry oxygen leading to fatigue
- provides protection against malaria
- homozygous is Sever
- Heterozygous is minor
Outline energy flow through a food chain
- energy from the sun is converted into chemical energy by photosynthesis
- heat is lost
- energy lost in hair, bones, faeces
- energy transfer is only 10% between trophic levels