3.4.7 Investigating diversity Flashcards
Comparing the base sequences of a gene provides more information than comparing the amino acid sequence for which the gene codes. Explain why
Different base triplets code for the same amino acids
What does standard deviation show?
Shows the spread of data about the mean
What can be said about the data collected if the standard deviation is large?
less reliable (data varies a lot)
What can be said about the data collected if the standard deviation is small?
more reliable (data varies very little)
If the standard deviations of the 2 sets of data collected overlaps what can be concluded?
no difference in the 2 sets of data, its not significant - due to chance
Variation is….
the differences between individuals
variation is caused by
genetics and the environment (or both)
Variation between organisms of the same species is due to …
differences in their alleles (and the environment)
variation between organisms of different species is due to…
different genes (and the environment)
When studying variation - can you study the whole population?
NO - take a sample
When you sample to study variation, how should you go about collecting the sample?
randomly
Taking samples at random ensures…
results are not biased
results are representative
When studying variation between 2 populations, what would you calculate?
mean
standard deviation
When plotting variation data, what type of graph do you get?
normal distribution curve
The highest point on a normal distribution curve (that is symmetrical) is ..
the mean value
If the standard deviation of the 2 sets of data DO NOT overlap what can you conclude from the data?
there is a difference between the data collected. It is likely significant and not due to chance?
What could you do to data collected if you wanted to determine if data collected was significant or not?
carry out a statistical test (the right one!)
When carrying out a statistical test what do you have to formulate first?
a null hypothesis
When comparing means of samples what statistical test would you do?
t test
When comparing observed and expected data what test would you perform?
chi squared test
When looking for a correlation between two variables what test would you do?
spearman’s rank
When drawing conclusions from statistical tests what words should you include in it?
significant or not
chance
probability
What level of probability to Biologists refer too?
5% / 0.05
If your calculate value in your tests is GREATER than the critical value in the table (at the 5% level), what can you conclude?
REJECT null
results are significant
less than a 5% probability that the differences are due to chance
If your calculate value in your tests is LESS than the critical value in the table (at the 5% level), what can you conclude?
Accept null
difference in the mean values are significant
greater than a 5% probability the difference is due to chance
if the P value is less than 0.02 what can you conclude
reject null
difference between mean values are significant
less than 2% probability that the difference
is due to chance
removal of hedgerows reduced diversity of birds - why?
- Removes species/types of plant/insect;
- Fewer food sources;
- Fewer habitats/niches;
How should a person collect and process data to investigate if there is a difference is size of seeds produced by a particular tree in 2 different areas?
- randomly sample seeds from both areas
- large sample size to ensure representative (reliable mean)
- measure mass of seed as indicator of size
- calculate mean and standard deviation
- T test carried out
- determine if there is a significant difference between the means of the two samples
Define species richness
number of different species in a community/habitat
give one limitation of using a line transect to collect data?
may avoid certain areas
what info does the bar representing standard deviation give about the plants in a sample?
spread of values around the mean height of plants
how would you know if the difference between mean heights of the plants grown from seeds was due to genetic differences?
plants measured were grown under uniform conditions
scientists collected bees using a method that was ethical and allowed them to identify accurately the species to which each belonged.
suggest a consideration the scientists had taken into account to make sure their method
allowed them to identify accurately the species to which each belonged?
- close examination
- key
SUGGEST and EXPLAIN 2 ways in which scientists could have improved their method used for data collection in an investigation?
- collect from more sites so TO increase accuracy
- count number of individuals of each species SO to calculate index of diversity
scientists tested their null hypothesis using the chi-squared statistical test. after 1 cycle their calculated chi-squared value was 350. the critical value at p=0.05 is 3.841
what does this result suggest about the difference between the observed and expected results and what can the scientist conclude?
- less than 0.05 PROBABILITY that DIFFERENCE between observed and expected due to CHANCE
- calculated value greater than critical value so REJECT null hypothesis
in an investigation, scientists investigated the possibility of breeding red clover plants that only produced 2n gamete.
use your knowledge of how directional selection may play a part in this?
- scientists selected for breeding plants that produced 2n gametes
- plants passed on alleles for production of 2n gametes to next gen
- frequency of alleles for production of 2n gametes increased
how would you collect a random sample of each population?
- use quadrat and transect
- use random number generator to generate coordinates
- place randomly at these intervals
- use 10 or more quadrats
