Cell Ultrastructure and Microscopy：練習問題

Which term describes the specific physical location of a gene on a chromosome?

A student observes a root tip squash containing 200 cells. The counts for cells in each stage of mitosis are: 15 in prophase, 5 in metaphase, 3 in anaphase, and 2 in telophase. What is the mitotic index for this sample?

Prokaryotic cells often possess a layer outside the cell wall called a capsule. Which of the following describes a primary function of the capsule in pathogenic bacteria?

Multicellular organisms are organized into a hierarchy of complexity. Which of the following examples represents the organ level of organization?

The acrosome reaction and the cortical reaction are essential steps in successful mammalian fertilisation. Which of the following describes a fundamental difference between these two reactions?

State two primary functions of the smooth endoplasmic reticulum (SER) within a eukaryotic cell.

Explain the fundamental difference between a totipotent stem cell and a pluripotent stem cell in terms of their differentiation potential.

Describe the sequence of events that occurs in the cortical reaction immediately following the fusion of the sperm cell membrane with the egg cell membrane, and explain why this is vital for successful development.

Cells are categorized as either prokaryotic or eukaryotic based on their internal structure and complexity.

(a) State two structural features present in a prokaryotic cell that are not found in a eukaryotic animal cell. (2)

(b) Both prokaryotic and eukaryotic cells contain ribosomes. Explain the role of ribosomes in these cells. (1)

A light microscope can be used to observe and measure biological specimens. To determine the size of a specimen, an eyepiece graticule must first be calibrated.

(a) Explain the steps required to calibrate an eyepiece graticule using a stage micrometer. (3)

(b) A student calculates that 40 divisions on the eyepiece graticule correspond to a total length of \( 100 \mu m \) on the stage micrometer. Calculate the length of one eyepiece division. (1)

(c) State one advantage of using an electron microscope instead of a light microscope when studying cell ultrastructure, and relate this to the concept of resolution. (1)