GEN LAB- PRELIMS

Which statement best defines a cell?

The basic unit of life

Which of the following organisms is composed of prokaryotic cells?

Bacteria

A major structural difference between prokaryotic and eukaryotic cells is that prokaryotic cells:

Lack a nucleus

Which structure is responsible for protein synthesis in prokaryotic cells?

Ribosomes

The cell envelope of a prokaryotic cell is composed of:

Cell wall and plasma membrane

What is the primary function of the plasma membrane?

Regulation of substances entering and leaving the cell

Which surface structure allows prokaryotic cells to move?

Flagella

Pili (fimbriae) are mainly involved in:

Attachment and genetic transfer

Which organelle is known as the “powerhouse of the cell”?

Mitochondria

Chloroplasts are found in plant cells and are responsible for:

Photosynthesis

Which organelle modifies, packages, and transports proteins?

Golgi complex

Lysosomes are primarily responsible for:

Waste digestion

During which phase of interphase does DNA replication occur?

S phase

Cells that permanently exit the cell cycle enter which phase?

G₀

Which type of cell division produces two genetically identical daughter cells?

Mitosis

The alignment of chromosomes at the cell’s equatorial plane occurs during:

Metaphase

Sister chromatids separate and move to opposite poles during:

Anaphase

The final outcome of mitosis is:

Two diploid identical cells

Which process produces gametes and increases genetic variation?

Meiosis

Crossing over occurs during which stage?

Prophase I of meiosis

Independent assortment of homologous chromosomes occurs during:

Metaphase I of meiosis

How many daughter cells are produced at the end of meiosis?

Four haploid

Which statement correctly compares mitosis and meiosis?

Meiosis results in genetic diversity

The main biological importance of meiosis is:

Sexual reproduction and variation

Chromosomes condense and become visible; the nuclear membrane begins to break down.

Prophase

Nuclear membranes reform around each set of chromosomes and chromosomes begin to decondense.

Telophase

Division of the cytoplasm resulting in two separate daughter cells occurs during:

Cytokinesis

Homologous chromosomes pair up, forming tetrads, and crossing over occurs.

Prophase I

Homologous chromosome pairs align at the equatorial plane.

Metaphase II

Homologous chromosomes separate while sister chromatids remain together.

Anaphase I

Two haploid cells are formed, each still containing sister chromatids.

Telophase I

Chromosomes condense again in haploid cells and spindle fibers form.

Prophase II

Chromosomes align at the equatorial plane of each haploid cell.

Metaphase II

Sister chromatids finally separate and move toward opposite poles.

Anaphase II

Nuclear membranes reform, producing four genetically different haploid cells.

Telophase II

In which phase is chromosome number reduced from diploid to haploid?

Anaphase I

Which phase is most responsible for genetic variation?

Prophase I

Which event occurs in meiosis but NOT in mitosis?

Pairing of homologous chromosomes

Which statement correctly compares the outcomes of mitosis and meiosis?

Mitosis produces genetically identical cells, while meiosis produces genetically different cells

A cell contains 46 chromosomes before division. After mitosis, each daughter cell will contain:

46 chromosomes

Which structure is directly responsible for ensuring equal chromosome distribution during cell division?

Spindle fibers

A failure of spindle fibers to attach properly during meiosis I would MOST directly affect:

Independent assortment of homologous chromosomes

Which phase would be MOST affected if crossing over did not occur?

Prophase I

A cell undergoing division shows homologous chromosomes separating, while sister chromatids remain attached. This cell is most likely in:

Anaphase I of meiosis

Which outcome would MOST likely result if meiosis did NOT reduce the chromosome number?

Chromosome number would double each generation

Gametes are formed through which specialized process?

Meiosis

How many chromosomes do human gametes contain?

23

Meiosis I is also called:

Reduction division

What term describes chromosomes in gametes that have the same genes but may carry different alleles?

Homologous chromosomes

Which of the following processes during meiosis contributes to genetic diversity by exchanging genetic material between homologous chromosomes?

Crossing over

Why is meiosis important for sexual reproduction?

It creates genetic diversity and reduces chromosome number

What ensures that offspring inherit the correct diploid chromosome number during fertilization?

Gametes being haploid

During meiosis, which mechanism ensures that each gamete carries a unique combination of alleles?

Crossing over between homologous chromosomes

A human gamete accidentally retains 24 chromosomes instead of 23. This error likely occurred during which stage of meiosis?

Meiosis I or Meiosis II nondisjunction

Which statement best explains why gametes must be haploid?

Haploid gametes restore diploid chromosome number upon fertilization

Independent assortment occurs during Metaphase I. What is its significance?

It shuffles maternal and paternal chromosomes randomly

Which of the following best explains why siblings from the same parents are genetically different?

Independent assortment and crossing over during meiosis

If a Drosophila gamete has 4 chromosomes, how many homologous pairs were present in its diploid germ cell before meiosis?

2

A scientist observes four cells after a division in a germ cell. Each cell has half the original chromosome number. This is most likely the result of:

Meiosis in a germ cell

Spermatogenesis and oogenesis are types of gametogenesis. What is a key difference between them?

Spermatogenesis produces four gametes per germ cell; oogenesis produces one viable gamete per germ cell

During gametogenesis, crossing over contributes to:

Generating genetic diversity

A nondisjunction event during gametogenesis can lead to:

Chromosomal abnormalities such as Down syndrome

Why is gametogenesis essential for sexual reproduction?

It maintains a stable chromosome number and allows genetic variation

Which process ensures that each haploid gamete contains only one set of chromosomes?

Meiosis and reduction division

Errors in gametogenesis can result in:

Infertility, chromosomal disorders, or developmental abnormalities

Which statement best describes the role of gametogenesis in evolution?

It generates variation that allows populations to adapt to changing environments

Why is Gregor Johann Mendel known as the Father of Genetics?

He formulated the fundamental rules of heredity through experiments with peas

The Law of Segregation states that:

Alleles for a trait separate during gamete formation, so each gamete carries only one allele

The Law of Independent Assortment describes:

How different gene pairs separate independently during gamete formation

Mendel’s experiments with peas were ideal because:

Peas have short lifespans, visible contrasting traits, and easy to control fertilization

If a monohybrid cross shows a 3:1 phenotypic ratio in the F2 generation, this is evidence of:

Segregation of alleles

In genetics, the Chi-square test is used to:

Compare observed genetic data with expected results to see if deviations are due to chance

Observed frequencies (O) in a Chi-square test refer to:

The actual counts collected from the experiment

Expected frequencies (E) are:

The numbers predicted based on Mendelian ratios or theoretical models

Degrees of freedom in a Chi-square test are calculated as:

Number of categories minus one

The probability multiplication rule is used when:

Calculating the chance of two independent events occurring together

Calculating the chance of either one of two mutually exclusive events occurring

Calculating the chance of either one of two mutually exclusive events occurring

Why is mastering the Chi-square test important for genetic studies?

It allows researchers to assess whether deviations from expected genetic ratios are significant or due to chance