Questions Correction 2023 Flashcards
A community definition
The name given to all of the organisms living in the same habitat
Describe how muscles in the iris help the person to see clearly when moving from a dimly lit to brightly lit area
Muscles in the iris contract
Reducing size of pupil so reduces amount of light entering
Plan an investigation to test the effect of drinking coffee on reaction time
1) Place elbow on the table holding a metre ruler and hold ruler above thumb
2) Test with different amounts of coffee
3) Repeat two more times and with at least two more students
4) Calculate mean values and compare reaction time with the different amounts of coffee drank
5) Control variables of the same age and same amount of sleep
What is tissue culture
A group of cells are grown into a new organism
Give the reason why a large number of people/chickens/animals is used
More valid/representative
Describe how selective breeding of chickens varieties A and B can produce a new variety of chicken
1) Breed best of A and B together
2) Select offspring with both the desired characteristics
3) Breed these offspring together
4) Repeat over several generations
Describe how carbon and nitrogen in compounds in the dead autumn leaves are recycled and used by living trees
1) Microorganisms cause decay, enzymes used in digestion
2) Respiration by microorganisms releases CO2 into the air
3) CO2 taken in by stomata and used in photosynthesis making glucose
4) Release nitrate ions into the soil
5) Nitrate ions taken in by roots via active transport
6) Nitrate ions used for making amino acids/ proteins
When milk decays lipids are broken down.
Explain why the pH changes more quickly when the temperature is higher
1) Enzymes more active
2) Lipids broken down more quickly
3) Fatty acids produced more quickly (which changes pH)
Explain how production of thyroxine causes an increase in body temperature
Thyroxine increases metabolic rate
Respiration releases energy
Explain how the decrease in concentration of ADH would causes the rate of urine production to be greater and the concentration of dissolved substances in urine to be less
Kidney tubes less permeable to water
So less water reabsorbed
More water in urine causing increased rate of production of urine
So more water in urine means lower concentration of dissolved substances
Why do scientists present their results as percentages
For comparison
Because different areas started with with different numbers
Explain why a lack of FSH in the women’s blood caused underdeveloped breasts
Lack of FSH causes lack of oestrogen
Breast development is dependent on oestrogen
Describe how meiosis produces cells that are genetically difficult
1) Random chromosomes from each pair of chromosomes
2) moves to one end of the cell
Explain how our understanding of evolution has developed due to fossil evidence and understanding the mechanisms of genetics
1) Fossils show evidence of life in the past
2) fossil record shows development of species over time and shows evidence of extinction
3) There are gaps in the fossil record which are being filled with new evidence such as evolutionary trees, description of fossil formation
4) Mendel’s breeding experiment with plants showed dominant and recessive alleles, chromosome behaviour and Mendel’s units work in similar ways, structure of DNA worked out
5) Genetic variation in a species due to a mutation and advantageous characteristics and alleles more likely to be passed
6) As seen in antibiotic resistant bacteria
