1. What is needed for most bacteria to multiply in food?
A. enough time on the right kind of food
B. lack of moisture on a food
C. an employee with an illness handling the food
2. When does a cell prepare to undergo meiosis to duplicates its chromosomes?
The Correct Answer and Explanation is :
- Correct answer: A. enough time on the right kind of food
Bacteria need a combination of time, food, and the right conditions (like warmth and moisture) to multiply. When food is left out too long, it provides the ideal environment for bacteria to grow. The bacteria feed on the nutrients present in the food, and the longer the food sits in the “danger zone” (between 40°F and 140°F), the more time bacteria have to multiply.
Bacteria thrive in moist environments, so lack of moisture (B) would typically inhibit growth, and while employees with illness (C) can introduce harmful bacteria, it is the food environment that most directly affects bacterial growth. Keeping food at the correct temperature, covering it to prevent contamination, and consuming or refrigerating it within a safe time limit are essential to preventing bacterial multiplication.
- Correct answer: Interphase (specifically the S phase)
Cells prepare to undergo meiosis during interphase, which consists of three stages: G1 (growth), S (synthesis), and G2 (second growth phase). During the S phase, the cell duplicates its chromosomes, so each chromosome consists of two identical sister chromatids. This step is crucial because, for meiosis to result in four genetically diverse haploid cells, the chromosome number must be halved, and having a duplicate set of chromosomes ensures the process can proceed correctly.
Before meiosis begins, the cell goes through a series of checkpoints in the cell cycle to ensure it is ready for division. In meiosis, there are two rounds of division: meiosis I and meiosis II. During meiosis I, homologous chromosomes (chromosomes that carry the same genes, one from each parent) are separated, reducing the chromosome number by half. In meiosis II, the sister chromatids are separated.
The process of chromosome duplication is essential to ensure that each daughter cell receives one complete set of chromosomes after meiosis. Without this replication in the S phase of interphase, cells could end up with incomplete or incorrect genetic material, potentially leading to errors like nondisjunction or aneuploidy (where cells have an abnormal number of chromosomes). This careful preparation allows for genetic diversity and proper cell function in sexually reproducing organisms.