Flashcards in April Test 3 Deck (47)
What does evolution mean?
A gradual change in the characteristics of a species over time
Why is it hard to find evidence of evolution?
Because some is destroyed by earthquakes
How is the age of a stone tool worked out?
By looking at the rock it's made with
What is genetic variation?
The characteristics of individuals vary in a population due to gene difference
What is natural selection?
By chance some individuals have variations that make them better at coping and more likely to survive
What is inheritance?
Naturally selected survivors breed and pass on their variations to offspring
What's the best way to remember the classification of an animal?
Kings Play Chess On Fire Grain Sand
What do plants have that animals don't?
Definition of species?
A group of similar organisms capable of reproducing
Definition of breed?
Members of an animal species differing from others slightly
Definition of variety?
Members of a plant species differing from others only slightly
What is artificial selection?
When humans breed organisms with useful characteristics to create new breeds/varieties with desired characteristics
Problems with selective breeding?
Takes a long time for desired characteristics
Large numbers may be disease prone
Concerns over animal welfare
What is a calorimetry?
The dry food flame experiment
What is diffusion?
Movement of particles from a high concentration to a low concentration
What is osmosis?
The net movement of water molecules across a partially permeable membrane from a high concentration to a low one
What is active transport?
The movement of particles across a membrane across a concentration gradient
Two differences between diffusion and active transport?
Active transport requires energy
In active transport particles are moved UP a concentration gradient not DOWN
What is a chromosome?
A coiled up length of DNA molecules
How do you calculate the number of cells produced by mitosis?
(n=number of divisions)
How is cancer caused?
When a cell starts dividing uncontrollably due to a change in one gene, causing a tumour
What is a stem cell?
An undifferentiated cell
Where are stem cells found?
Risks of stem cells?
They divide very quickly
They may carry disease
The body may reject them
How does a reflex happen?
Why is alcohol added to DNA?
To get the DNA out as it isn't soluble in alcohol
What decides the order of amino acids in a protein?
The order of the bases
Instead of T what does mRNA use?
•RNA polymerase binds to a region of DNA in front of a gene
•The two DNA strands unzip
•The RNA polymerase uses the coding DNA as a template to make mRNA
•The mRNA leaves the nucleus and joins with a ribosome