SCIENCE TEST 2

1. Explain the process of selective breeding and identify some of the benefits.

Question: What is selective breeding, and what are some benefits and potential drawbacks of this process?

Answer: Selective breeding (or artificial selection) is the process where humans choose specific organisms with desirable characteristics to breed, in order to pass on those traits to the next generation.

Benefits:

  • Improved Traits: Selective breeding can result in offspring with enhanced traits, such as disease resistance in plants or animals that produce higher yields.

  • Desired Characteristics: It allows for the enhancement of specific traits, such as size, color, or temperament.

  • Increased Productivity: In agriculture, selective breeding can increase crop yields or livestock productivity.

Potential Drawbacks:

  • Inbreeding: Repeatedly breeding closely related individuals can lead to genetic defects due to a limited gene pool.

  • Reduced Genetic Diversity: Over time, selective breeding can decrease the diversity of a species, making it more vulnerable to disease or environmental changes.

 

2. Describe the process of natural selection.

Question: Explain how natural selection leads to the survival of the fittest in a population.

Answer: Natural selection is the process by which organisms with advantageous traits are more likely to survive and reproduce. The steps of natural selection are as follows:

  1. Variation: Within any population, individuals show genetic variation (differences in traits).

  2. Selective Agent/Pressure: An environmental factor (such as a predator or climate change) acts as a selective agent or pressure that affects survival.

  3. Adaptation: Some individuals have traits that give them an advantage in the specific environment, helping them survive better than others.

  4. Survival of the Fittest: The individuals with advantageous traits are more likely to survive and reproduce, passing those traits on to the next generation.

  5. Change Over Generations: Over time, the population will evolve as more individuals with beneficial traits make up the gene pool.

 

3. Identify and describe selection pressures in a given context.

Question: What are selection pressures, and how do they influence the traits of a population?

Answer: Selection pressures are factors in the environment that influence the survival and reproduction of organisms. These can be biotic (living factors like predators, competition, or disease) or abiotic (non-living factors like temperature or food availability).

Example: In an environment with scarce food resources, animals with traits that allow them to access or utilize food more efficiently may survive and reproduce. For instance, birds with larger beaks might survive better if larger seeds are the main food source. Over time, the population of birds may have more individuals with larger beaks due to this selection pressure.

 

4. Differentiate between natural selection and speciation.

Question: How do natural selection and speciation differ?

Answer: Natural Selection is the process where organisms with beneficial traits have a higher chance of survival and reproduction, leading to changes in a population over time.

Speciation, on the other hand, is the formation of new species from an existing population. Speciation occurs when a population becomes reproductively isolated, usually through geographic or behavioral isolation, and diverges genetically over time due to different selection pressures. Once genetic differences accumulate, the isolated populations can no longer interbreed, leading to the emergence of new species.

 

5. Summarise the process through which speciation occurs.

Question: What are the steps involved in the process of speciation?

Answer: Speciation occurs through the following steps:

  1. Isolation: A population becomes physically or behaviorally isolated (e.g., by a river or mountain range) and can no longer interbreed with other members of the species.

  2. Genetic Divergence: Over time, the isolated populations accumulate genetic differences due to different selection pressures or mutations.

  3. Selection: The separated populations are exposed to different environmental conditions, leading to the development of different traits in each population.

  4. Reproductive Isolation: Eventually, these genetic differences may become so significant that the populations can no longer interbreed, even if they come back into contact.

  5. Formation of New Species: At this point, the two populations are considered separate species.

 

6. Summarise and provide examples of evidence supporting the theory of evolution.

Question: What evidence supports the theory of evolution?

Answer: Several types of evidence support the theory of evolution:

  1. Homologous Features: Organisms that share similar anatomical structures (e.g., the limbs of humans, whales, and bats) suggest a common ancestor. These homologous features have been adapted for different functions but originate from the same ancestral structure.

  2. Analogous Features: Features that serve the same function but have different evolutionary origins, such as the wings of bats and insects, indicate that similar environmental pressures can lead to similar adaptations.

  3. Embryology: Similarities in the early stages of development in different species (e.g., humans, chickens, and fish) suggest a common origin.

  4. Comparative Anatomy: Comparing the body structures of different species helps reveal evolutionary relationships. For example, the structure of the vertebrate skeleton suggests a shared ancestry.

  5. Fossil Evidence: Fossils show how species have changed over time, providing a record of past life forms and demonstrating the gradual changes that have occurred over millions of years.