(a) (i) In genetics, what is meant by the term haploid? (ii) What is a chromosome? (b) Read the paragraph below and answer the questions that follow - Leaving Cert Biology - Question 11 - 2012

A chromosome is a structure composed of DNA and protein that contains genes. Chromosomes are often visualized as large, thread-like formations that exist in pairs, with one from each parent, playing a crucial role in heredity and cell division.

Albinism is characterized by a lack of pigment in the skin, fur, and eyes. The primary features include:

1. White or lack of pigment in skin/fur/eyes.
2. The condition is expressed only in the homozygous state and is not dominant, meaning both alleles must be for albinism for the trait to be displayed.

A recessive gene is one that must be inherited from both parents to be expressed in the phenotype of an organism. If an individual possesses one dominant allele and one recessive allele, the dominant trait will prevail, masking the presence of the recessive trait.

A mutation is a change that occurs in the DNA sequence of a gene or chromosome, which can lead to variations among organisms. These variations can be beneficial, neutral, or harmful and play a significant role in evolutionary processes.

Evolution refers to the change in the heritable traits of biological populations over successive generations. It is driven by processes such as natural selection, where individuals better adapted to their environment tend to survive and reproduce more successfully.

Charles Darwin is one of the scientists who first explained how evolution occurs through the mechanism of natural selection, providing foundational insights into the process.

One source of evidence for evolution is the fossil record, which shows patterns of change in species over time, including transitional forms that display characteristics of both ancestral and derived species.

Genetic engineering is the direct manipulation of an organism's genome using biotechnology. It involves altering the genetic material of an organism to introduce new traits, improve existing traits, or produce desired biological products.

Three main procedures used in genetic engineering are:

1. Isolation of DNA from the organism.
2. Cutting DNA using restriction enzymes.
3. Transformation, where new genetic material is introduced into the target organism.

Examples of genetic engineering applications include:

1. Development of genetically modified crops, such as Long-life tomatoes that have increased shelf life.
2. Creation of crops resistant to pests, such as Weedkiller-resistant crops, which minimize the need for chemical herbicides.