10 NAS Term 1 Biology: Cells, Heredity, and Evolution

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Questions and Answers

Explain how the structure of the cell membrane contributes to its function as a selective barrier.

The cell membrane is composed of a phospholipid bilayer with embedded proteins. The hydrophobic tails of the phospholipids repel water-soluble substances, while the proteins act as channels or carriers for specific molecules.

Describe the key structural differences between prokaryotic and eukaryotic cells and explain how these differences impact their functions.

Prokaryotic cells lack a nucleus and other membrane-bound organelles, while eukaryotic cells possess these structures. This structural difference allows for more complex functions and compartmentalization of processes in eukaryotic cells.

A student observes a cell under a microscope with a 10x eyepiece and a 40x objective lens. Calculate the total magnification and describe what this magnification allows them to see clearly.

The total magnification is 400x. At this magnification, the student can see individual cells, their nuclei, and some larger organelles like mitochondria or chloroplasts.

Explain the significance of the S phase in the cell cycle concerning DNA replication and its impact on cell division.

During the S phase, DNA replication occurs, resulting in two identical copies of each chromosome. This ensures that each daughter cell receives a complete and identical set of genetic information during cell division. Signup and view all the answers

Compare and contrast the outcomes of mitosis and meiosis in terms of the number of daughter cells produced and their genetic content.

Mitosis produces two genetically identical daughter cells, while meiosis produces four genetically different daughter cells. Mitosis is for growth and repair, whereas meiosis is for sexual reproduction and genetic diversity. Signup and view all the answers

In a monohybrid cross, where one parent is homozygous dominant (AA) and the other is heterozygous (Aa), what are the possible genotypes and phenotypes of their offspring?

The possible genotypes are AA and Aa. The phenotype would be dominant in both cases, since the dominant allele will mask the recessive allele. Signup and view all the answers

Explain how genetic variation arises during meiosis and its importance for evolution.

Genetic variation arises during meiosis through crossing over and independent assortment. This variation is crucial for natural selection, as it provides the raw material for adaptation and evolution. Signup and view all the answers

Describe how natural selection can lead to adaptation in a population of organisms over time.

Natural selection favors individuals with traits that enhance their survival and reproduction in a specific environment. Over time, the frequency of these advantageous traits increases in the population, leading to adaptation. Signup and view all the answers

Explain how antibiotic resistance in bacteria provides evidence for evolution.

The overuse of antibiotics creates a selective pressure that favors bacteria with resistance genes. These bacteria survive and reproduce, leading to an increase in the proportion of antibiotic-resistant bacteria in the population, which demonstrates natural selection and evolution. Signup and view all the answers

How do homologous structures support the theory of evolution?

Homologous structures, such as the bones in the forelimbs of different mammals, share a common ancestry but have evolved to perform different functions. Their similarities suggest descent from a common ancestor, supporting evolution. Signup and view all the answers

Flashcards

Cell

Basic unit of life, can be prokaryotic or eukaryotic.

Organelles

Structures within a cell that perform specific functions (e.g., mitochondria, chloroplasts).