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In 1997, 11 males were counted and this increased to 221 males in 2021 - Edexcel - GCSE Biology - Question 6 - 2023 - Paper 1
Question 6
In 1997, 11 males were counted and this increased to 221 males in 2021. (i) Calculate the percentage increase in the number of males from 1997 to 2021. (ii) This c... show full transcript
Worked Solution & Example Answer:In 1997, 11 males were counted and this increased to 221 males in 2021 - Edexcel - GCSE Biology - Question 6 - 2023 - Paper 1
Step 1
Calculate the percentage increase in the number of males from 1997 to 2021.
Answer
To calculate the percentage increase, use the formula:
ext{Percentage Increase} = rac{ ext{New Value} - ext{Old Value}}{ ext{Old Value}} imes 100Here, the New Value is 221 and the Old Value is 11.
Calculating:
egin{align*}
ext{Percentage Increase} & = rac{221 - 11}{11} imes 100
& = rac{210}{11} imes 100
& ext{approximately } 1909.09
& ext{Thus, the percentage increase is } 1909.1
ext{(rounded to one decimal place)}.
ext{Answer: } 1909.1
\
Step 2
Explain, using your knowledge of natural selection, why being closely related could make the bitterns susceptible to extinction.
Answer
Being closely related means that the bitterns are genetically similar, which can reduce genetic diversity.
Reasons for Susceptibility:
- Increased Risks from Disease: With less genetic variation, a disease that affects one bittern is more likely to affect all of them, leading to a higher risk of mortality.
- Limited Adaptability: Genetic similarity limits the ability of the population to adapt to environmental changes or threats, such as climate change or habitat destruction.
- Reduced Reproductive Success: If closely related individuals mate, it may lead to inbreeding, resulting in offspring that are less viable or fertile.
Overall, these factors can lead to a decrease in population size, making them more susceptible to extinction.
Step 3
Describe how selective breeding can be used to produce a large population of animals that are not closely related.
Answer
Selective breeding involves choosing specific animals with desirable traits to reproduce. This can be done by:
- Diverse Genetic Pool: By selecting animals from different genetic backgrounds, breeders can create a more diverse genetic pool, which helps avoid inbreeding.
- Crossbreeding: Breeding animals from different breeds or varieties can increase genetic variability and reduce the chances of genetic disorders.
- Controlled Breeding Programs: Implementing breeding programs that monitor genetic lines can help ensure that animals produced are not closely related.
These strategies help maintain a broader genetic diversity within the population, reducing the risks of extinction.
Step 4
Complete the Punnett square to show how sex is determined in birds.
Answer
Here is the completed Punnett square representing the sex determination in birds:
| Z | W |
------------------------
Z | ZZ | ZW |
------------------------
Z | ZZ | ZW |
Interpretation:
- ZZ represents male offspring.
- ZW represents female offspring.
This demonstrates how the sex is genetically determined based on the alleles inherited from the parents.