3.1 Some horses have straight hair and others have curly hair - NSC Life Sciences - Question 3 - 2021 - Paper 2

The significance of removing the nucleus from the ovum of horse T before inserting the nucleus from horse S is to ensure that only the desired DNA, which contains the trait for straight hair, is present in the clone. This prevents any genetic contribution from horse T, ensuring the cloned horse maintains the characteristics from horse S.

The cloned offspring will be genetically identical to horse S since the nucleus from horse S contains all the genetic material that dictates its characteristics.

1. Cloning allows for the production of animals with desirable traits, such as health and nutrition.
2. It helps conserve endangered species by allowing for the replication of genetic material that might otherwise be lost.

The evidence represented here is biogeography, which shows how species are distributed across different geographical areas and suggests common ancestry.

A biological species is defined as a group of organisms that can interbreed and produce fertile offspring, sharing a common gene pool.

These three species likely evolved from a common ancestor that lived on a large continent. Once separated by geographical barriers, each population underwent natural selection in response to different environmental conditions, leading to varied adaptations that diversified into distinct species.

Higher doses of antibiotics decrease the number of harmful bacteria more effectively, leading to healthier cattle. This reduces disease-related losses, lowers veterinary costs, and ultimately increases the farmer's profit margin through improved cattle health and productivity.

The continuous use of antibiotics creates pressure on bacterial populations, leading to natural selection where only the resistant bacteria survive. As these resistant bacteria reproduce, they pass on their resistance, resulting in a population that can withstand antibiotic treatment.

(a) Independent variable: Gall size (mm) (b) Dependent variable: Percentage of gallfly larvae killed by predatory birds (%)

One advantage of larger gall size is that it provides better protection from predatory birds, increasing the survival rate of gallfly larvae.

The size of galls produced is an example of continuous variation because galls can vary in size within a range, instead of being limited to distinct categories, showcasing a spectrum of sizes influenced by genetic and environmental factors.

Larger galls may be more visible to predatory birds, leading to a higher percentage of larvae being eaten. On the other hand, smaller galls may be less visible, potentially decreasing the risk of predation.

A line graph should be plotted with gall size on the x-axis and the percentage of gallfly larvae killed on the y-axis, representing the trend that larger galls initially increase predation rates, then a decline occurs.

(a) Skulls of bipedal organisms: X, Z (b) Pelvic structure of a quadrupedal organism: C

The pelvic structure of a quadrupedal organism (C) is adapted for supporting the weight of the body in a horizontal position, allowing for efficient locomotion on four limbs.

Bipedal organisms, such as humans, have a longer and narrower pelvis adapted for upright walking, while quadrupedal organisms have a wider pelvis that supports a horizontal posture and facilitates movement on four limbs.