Question

The observable traits expressed by an organism are described as its ________. a. phenotype b. genotype c. alleles d. zygote

Short answer

The correct term is a. phenotype. Phenotype refers to the observable traits exhibited by an organism, resulting from the interaction between its genetic makeup (genotype) and the environment.

Step-by-step solution

Identify the correct term

Based on the given definition "the observable traits expressed by an organism," the correct term is a. phenotype.

Define the chosen term (phenotype)

Phenotype refers to the observable traits exhibited by an organism, resulting from the interaction between its genetic makeup (genotype) and the environment.

Briefly explain the other terms for better understanding

It can be helpful to understand the differences between the other terms given in the exercise as well: b. genotype - The genetic makeup of an organism, including the specific genes or alleles that it has inherited from its parents. c. alleles - Different forms of a gene that can be found at a particular locus (spot) on a chromosome. d. zygote - The initial cell formed when two gametes (sperm and egg cells) combine during fertilization. The zygote contains all the genetic information needed to form a new individual. By understanding the differences between these terms, it becomes clear that the best answer to the exercise is a. phenotype, as it refers to the observable traits expressed by an organism.

Key concepts

Genotype

Genotype refers to the entire genetic makeup of an individual. It's like a blueprint that determines the potential traits an organism might express. These traits are not always visible but reside in the organism's DNA.
Genotype consists of the genes passed down from one generation to the next. Many factors contribute to a genotype, including:

• Inherited genes: These come from the organism's parents.
• Combination of alleles: Various forms of genes that interact with each other.

While the genotype itself is not visible, it plays a crucial role in determining the phenotype. However, the environment can also influence how genes are expressed in the phenotype. For example, two identical plants with the same genotype might grow differently if one receives more sunlight and water than the other.

Alleles

Alleles are the different versions of a gene found at the same place, or locus, on a chromosome. It's helpful to think of alleles as variations within the same recipe. While they all achieve a similar function, each may lead to a different outcome or trait.
Each individual inherits two alleles for each gene, one from each parent. These can either be:

• Dominant alleles: These tend to mask the effect of recessive alleles when present.
• Recessive alleles: These are expressed only when two copies are present without a dominant allele.

For example, for a gene determining flower color, one allele might result in red petals, while another might result in white. If the red allele is dominant, the plant's flowers will appear red even if it has one white allele. Understanding alleles is key in predicting genetic traits and variations within a population.

Zygotic Development

Zygotic development is an essential stage in the life cycle of an organism. It begins with the formation of a zygote, the first cell formed when a sperm and an egg unite during fertilization.
This unicellular organism, the zygote, eventually develops into a complex multicellular organism through several stages. Important aspects of zygotic development include:

• Cell division: The zygote rapidly divides into more cells.
• Differentiation: Cells begin to specialize and take on specific roles.
• Growth: The organism grows from a tiny single cell into a full organism, continuing to develop its structures and functionalities.

Zygotic development ensures that genetic information from both parents is combined and expressed, leading to the formation of a new individual. This process is crucial as it lays down the foundation for all subsequent growth and development of the organism.