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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

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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. This could ... 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.

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Answer

To determine the percentage increase in the number of males, we can use the formula:

extPercentageIncrease=(New ValueOld ValueOld Value)×100 ext{Percentage Increase} = \left( \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \right) \times 100

Substituting the given values:

  1. Calculate the increase:

    • New Value = 221
    • Old Value = 11
    • Increase = 221 - 11 = 210
  2. Calculate the percentage:

    • Percentage Increase = (210 / 11) x 100 = 1909.1%

Thus, the percentage increase in the number of males from 1997 to 2021 is approximately 1909.1%.

Step 2

Explain, using your knowledge of natural selection, why being closely related could make the bitterns susceptible to extinction.

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Answer

Being closely related can lead to reduced genetic diversity within a population. This lack of variation means that:

  1. Limited Adaptability: If all individuals are genetically similar, the population may struggle to adapt to changes in the environment or disease, making them more vulnerable.
  2. Increased Susceptibility to Disease: A genetic similarity can mean that if one individual is affected by a disease, others may also be affected similarly, leading to a higher mortality rate.
  3. Fewer Offspring: The limited genetic diversity could lead to problems in reproduction, resulting in fewer offspring that may survive, further decreasing the population size.
  4. Inability to Evolve: With little genetic variation, the population may not evolve over time, leaving them unable to cope with environmental changes or pressures.

Altogether, these factors may increase the risk of extinction for closely related individuals, as they lack the genetic breadth necessary for survival.

Step 3

Describe how selective breeding can be used to produce a large population of animals that are not closely related.

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Answer

Selective breeding can be utilized to create a large population of animals that are not closely related by following these steps:

  1. Choosing Diverse Parent Stock: By selecting parent animals from different genetic backgrounds, breeders can promote genetic diversity within the offspring.
  2. Crossbreeding: Introducing individuals of different breeds or strains can further enhance genetic variation by combining different alleles.
  3. Avoiding Inbreeding: By monitoring the genetic lineage of breeding stock, breeders can minimize inbreeding, which helps to maintain a genetically diverse population.

This process results in a population that exhibits a broader range of traits and increased vitality, reducing the likelihood of extinction, and promoting a healthier breeding population.

Step 4

Complete the Punnett square to show how sex is determined in birds.

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Answer

ZW
ZZZ (male)ZW (female)
ZZZ (male)ZW (female)

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