MTTC Biology Flashcards

In a food web, an organism that can occupy both the second and third trophic levels is called a(n):

Answer: Omnivore

Omnivores consume both plants (acting as primary consumers) and animals (acting as secondary consumers), so they occupy multiple trophic levels.

Which of the following best describes the function of the lac operon in E. coli?

Answer: It regulates expression of lactose-metabolizing enzymes

The lac operon controls transcription of genes needed to metabolize lactose; it is induced when lactose is present and glucose is absent.

A cell placed in a hypotonic solution will:

Answer: Gain water by osmosis and may lyse

In a hypotonic solution, water moves into the cell by osmosis (from higher water potential outside to lower inside), causing the cell to swell and potentially burst.

Which of the following correctly describes C4 photosynthesis compared to C3 photosynthesis?

Answer: C4 plants pre-fix CO2 in mesophyll cells to reduce photorespiration

C4 plants fix CO2 into a 4-carbon compound in mesophyll cells and deliver it to bundle sheath cells, concentrating CO2 and minimizing photorespiration.

A student is performing a chi-square test on genetic cross data. If the calculated chi-square value is less than the critical value, the student should conclude:

Answer: The results support the null hypothesis of expected ratios

A chi-square value below the critical value indicates that observed deviations from expected ratios are due to chance, supporting the null hypothesis.

Which layer of the skin contains melanocytes responsible for producing skin pigment?

Answer: Stratum basale

Melanocytes are found in the stratum basale (deepest epidermal layer) and produce melanin, which is transferred to keratinocytes to protect against UV radiation.

Which process describes bacteria gaining new genetic material through direct cell-to-cell contact via a pilus?

Answer: Conjugation

Conjugation is the transfer of genetic material (often plasmids) between bacterial cells through a physical connection called the sex pilus.