Microscopic Observations of Mitosis 2

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Questions and Answers

What is the primary function of immersion oil in microscopy?

To lubricate the lens and prevent scratches during movement.

To increase the refractive index of the medium between the objective lens and the specimen, minimizing light scattering and improving resolution. (correct)

To act as a sealant, preventing the entry of dust and particles into the microscope.

To enhance the contrast of the image by absorbing specific wavelengths of light.

What is the relationship between the resolving power of a microscope and the minimum distance between two objects that can be seen as separate entities?

The resolving power is independent of the minimum distance, meaning the ability to distinguish objects is unrelated to the distance between them.

The resolving power is directly proportional to the minimum distance, meaning a higher resolving power requires objects to be farther apart to be distinguished.

The resolving power is inversely proportional to the minimum distance, meaning a higher resolving power allows for the distinction of objects closer together. (correct)

The resolving power is a logarithmic function of the minimum distance, meaning there is a non-linear relationship between them.

What is the total magnification of a microscope with an objective lens magnification of 40x and an eyepiece magnification of 10x?

400x (correct)

50x

10x

40x

Which mechanical component of a microscope is responsible for adjusting the position of the condenser vertically?

The mechanical system of the condenser (A) Signup and view all the answers

What is the primary function of the mechanical stage in a microscope?

To move the specimen horizontally in the X and Y axes. (D) Signup and view all the answers

What is the typical magnification range of ocular lenses?

2x - 30x (B) Signup and view all the answers

Which of the following is NOT a key component of the mechanical elements of a microscope?

The ocular lens (C) Signup and view all the answers

Which component of the microscope is responsible for creating the magnified image that is viewed through the eyepiece?

The objective lens (C) Signup and view all the answers

What is the primary function of the lighting system in an optical microscope?

To illuminate the observed object optimally (A) Signup and view all the answers

Which component of the microscope is responsible for concentrating light to illuminate the specimen?

The condenser (C) Signup and view all the answers

How do immersion lenses enhance the observation of a specimen?

By requiring a liquid between the lens and specimen (C) Signup and view all the answers

What type of image do lenses in a microscope create?

Both B and C (C) Signup and view all the answers

What is the role of the diaphragm in a microscope?

To adjust the amount of light entering the condenser (C) Signup and view all the answers

Which type of lens typically allows for higher magnification in microscopy?

Wet (immersion) lenses (B) Signup and view all the answers

What is the typical maximum magnification achieved by dry lenses?

60 times (C) Signup and view all the answers

What is the significance of using immersion oil in microscopy?

It reduces light refraction and improves resolution (C) Signup and view all the answers

What happens during the G1 phase of interphase?

Cell mass and volume increase intensively. (B) Signup and view all the answers

Which phase immediately precedes the M phase in the cell cycle?

G2 phase. (A) Signup and view all the answers

During which phase does the DNA content increase from 2n to 4n?

S phase. (A) Signup and view all the answers

What characterizes the G0 phase of the cell cycle?

Cells undergo significant metabolic functions without division. (A) Signup and view all the answers

What key event occurs during the transition from the G2 phase to the M phase?

Cell cycle checkpoints ensure readiness for division. (B) Signup and view all the answers

In which of the following situations might a cell enter the G0 phase?

The cell's genetic material is damaged. (B) Signup and view all the answers

What are the two main processes that make up the M phase?

Karyokinesis and cytokinesis. (C) Signup and view all the answers

What occurs during the G2 phase before mitosis starts?

Cellular organelles are synthesized and prepared. (D) Signup and view all the answers

What occurs during prophase in mitosis?

Chromatin condenses and doubles chromosomes become visible (D) Signup and view all the answers

What is the main event that characterizes prometaphase?

Nuclear envelope breakdown occurs (C) Signup and view all the answers

During which phase do chromatids align at the equatorial plane?

Metaphase (C) Signup and view all the answers

What happens during anaphase?

Sister chromatids separate and move to opposite poles (D) Signup and view all the answers

Which process follows telophase in cell division?

Cytokinesis (D) Signup and view all the answers

What is the role of the contractile ring in cytokinesis?

It constricts to divide the cell into two daughter cells (D) Signup and view all the answers

Which structures allow chromatids to attach to spindle microtubules during prometaphase?

Kinetochores (D) Signup and view all the answers

What happens to the chromosomes at the conclusion of telophase?

They are organized into the nuclear envelope (A) Signup and view all the answers

What is the primary function of the G1 phase in the cell cycle?

Preparation for DNA replication occurs. (D) Signup and view all the answers

Which phase of the cell cycle is characterized by chromosome condensation?

M phase (A) Signup and view all the answers

During which phase of the cell cycle do metabolic activities peak and chromosomes are in a non-condensed state?

Interphase (C) Signup and view all the answers

What is the outcome of the S phase in the cell cycle?

Chromatid doubling occurs. (A) Signup and view all the answers

What role does the cell-cycle control system serve?

Ensures the proper sequence of cell cycle events. (D) Signup and view all the answers

Which of the following best describes the function of the G2 phase?

It serves as a checkpoint before mitosis. (A) Signup and view all the answers

What is a key characteristic of the chromatin state during interphase?

It is in a non-condensed state and not visible. (D) Signup and view all the answers

How does the cell cycle contribute to the growth and regeneration of organisms?

By doubling the DNA content precisely. (C) Signup and view all the answers

During which phase of mitosis do chromosomes align at the equatorial plane of the cell?

Metaphase (B) Signup and view all the answers

What is the key characteristic of anaphase in mitosis?

Chromatids are separated and pulled to opposite poles (B) Signup and view all the answers

In which mitotic phase do chromosomes condense and become visible under a microscope?

Prophase (A) Signup and view all the answers

Which phase follows metaphase during mitosis?

Anaphase (C) Signup and view all the answers

What happens to the nuclear envelope during prophase?

It dissolves, allowing chromosomes to move freely (C) Signup and view all the answers

Which of the following best describes telophase in mitosis?

Chromosomes reach opposite poles and begin to de-condense (A) Signup and view all the answers

What do we observe during cytokinesis?

Cell membrane pinches inwards to separate the daughter cells (A) Signup and view all the answers

How are double and single chromatids present during the stages of mitosis?

Both double and single chromatids appear in anaphase (D) Signup and view all the answers

Study Notes

Microscopic Observations of Mitotic Divisions

Theoretical Part: A student should know the structure of an optical microscope and the phases of mitosis.

Microscope Construction

Optical and Mechanical Systems: Microscopes combine optical (lighting and magnifying) and mechanical (positioning) systems.
Optical System: The first part focuses on optimal illumination, the second magnifies the image.
Mechanical System: Positioning of individual optical system elements.
Image Characteristics: The resulting image is magnified, and virtual.

Optical Elements

Light Source: Modern microscopes use a built-in light bulb with a reflector. Light intensity adjusts based on magnification.
Condenser: A set of lenses concentrate light into a cone to illuminate the specimen.
Diaphragm: Controls the amount of light entering the condenser.
Lenses: Magnify the image, creating a real image of the specimen. Dry lenses magnify up to 60 times, immersion lenses up to 150 times. Immersion oil is used with immersion lenses for enhanced resolution up to 0.16 µm.
Ocular Lens (Eyepiece): Creates a virtual magnified image; magnification typically ranges from 2-30 times.
Immersion Oil: Used with immersion lenses, increasing resolution.

Mechanical Elements

Base and Arm: Provide structural rigidity.
Mechanical Stage: Allows for horizontal movement to change the field of view.

Cell Cycle

Interphase: The period between mitotic divisions. It involves G1 (pre-DNA synthesis), S (DNA synthesis), and G2 (pre-division) phases.
M Phase (Mitosis): The actual division of the cell nucleus. Consists of prophase, prometaphase, metaphase, anaphase, and telophase, followed by cytokinesis.

Mitosis Phases

Prophase: Chromatin condenses, chromosomes become visible, and the mitotic spindle forms outside the nucleus.
Prometaphase: The nuclear envelope breaks down. Chromosomes attach to the spindle microtubules.
Metaphase: Chromosomes align in the equatorial plane of the spindle.
Anaphase: Sister chromatids separate and move to opposite poles of the cell.
Telophase: Daughter chromosomes reach the spindle poles, new nuclear envelopes form, and two nuclei are formed.

Cytokinesis

Cytoplasmic Division: The cell cytoplasm divides, creating two daughter cells, each with one nucleus.

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Description

This quiz covers the structural components of optical microscopes and the phases of mitosis. Participants will explore the mechanical and optical systems involved in microscopy, as well as the functionalities of various optical elements like light sources and lenses. Test your knowledge of how these components work together to facilitate microscopic observations.