Biology Chapter on Cell Size and Division

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Questions and Answers

During which phase of mitosis do chromosomes align at the cell's center?

Telophase

Cytokinesis

Metaphase (correct)

Anaphase

What is the primary function of centrioles during cell division in animal cells?

To form cell plates

To attach spindle fibers (correct)

To initiate cell membrane pinching

To duplicate chromosomes

What is the outcome concerning chromosome numbers when two haploid gametes fuse during sexual reproduction?

The zygote has half the number of chromosomes as the parent cells.

The zygote has the same number of chromosomes as the sex cells.

The zygote restores the diploid number of chromosomes. (correct)

The zygote has twice the number of chromosomes as the parent cells.

Which process is responsible for the exchange of genetic material between homologous chromosomes?

Crossing over Signup and view all the answers

What is the function of regulatory proteins in the cell cycle?

To control the cell cycle, both inside and outside the cell Signup and view all the answers

What is the primary function of cyclins in the cell cycle?

To regulate the progression of the cell cycle. Signup and view all the answers

Which of the following describes the action of internal regulators in the cell cycle?

They ensure all necessary steps of a phase are completed before the next phase begins. Signup and view all the answers

How are external regulators different from internal regulators in the cell cycle?

External regulators direct the cell to speed up or slow down the cell cycle in response to signals from outside the cell, while internal respond to signals from inside the cell. Signup and view all the answers

What distinguishes apoptosis from uncontrolled cell growth seen in cancer?

Apoptosis is a controlled method of self-destruction, while uncontrolled growth occurs without regulation. Signup and view all the answers

A tumor is classified as benign when it exhibits which characteristics?

It does not spread to surrounding healthy tissues or other parts of the body. Signup and view all the answers

What formula is used to calculate the surface area of a cell?

L x W x 6 Signup and view all the answers

What problem can occur when a cell's volume grows too rapidly relative to its surface area?

Insufficient material exchange Signup and view all the answers

What is the main advantage of asexual reproduction in a stable environment?

Genetically identical offspring thrive Signup and view all the answers

In sexual reproduction, where does offspring genetic information come from?

A blend of genetic information from two separate parent cells Signup and view all the answers

What happens to DNA in a prokaryotic cell during cell division?

Packaged into a single, circular chromosome and duplicated Signup and view all the answers

During which phase of the eukaryotic cell cycle does DNA replication occur?

S phase Signup and view all the answers

What key event occurs during the prophase stage of mitosis?

Chromosomes become visible and the spindle beings to form Signup and view all the answers

What is the relationship between cell size and its efficiency in moving materials across its membrane?

The larger a cell, the less efficient it is in transporting materials across its membrane Signup and view all the answers

Study Notes

Cell Size and Efficiency

Larger cells are less efficient at moving materials across their membrane and place greater demands on their DNA.
Surface area is calculated as length × width × 6 (SA).
Volume is calculated as length × width × height (V).
The ratio of surface area to volume (SA:V) is crucial for cellular function. A smaller SA:V ratio leads to inefficiencies.

Information and Traffic Problems

Cell volume growth outpaces the increase in surface area.
This creates difficulty in exchanging materials.
This leads to an information crisis as the cell struggles to manage its internal processes.

Cell Division

Cell division creates two daughter cells.
DNA replication must precede cell division.
Dividing into smaller cells maintains a high surface area to volume ratio, ensuring efficient material exchange.

Asexual Reproduction

A single parent produces genetically identical offspring.
Offspring can be produced rapidly in favorable conditions.
In stable conditions, this method is highly effective.

Sexual Reproduction

Involves the fusion of two parent cells.
Offspring inherit genetic information from both parents.
This provides genetic diversity.
This is advantageous in changing environments.

Comparing Asexual and Sexual Reproduction

Feature	Asexual	Sexual
Offspring Production	Many offspring rapidly	Fewer offspring
Need for Mate	No	Yes
Genetic Diversity	Low	High
Adaptation to Change	Less adaptable	More adaptable

Chromosomes

Genetic information is bundled into packages of DNA
Prokaryotic cells have a single, circular chromosome.
Eukaryotic cells have multiple thread-like chromosomes.
Prokaryotic cells reproduce through binary fission.

Eukaryotic Cell Cycle

Interphase is the period between cell divisions.
Mitosis is the division of the nucleus.
Cytokinesis is the division of the cell.
G1 Phase: cell grows in size, produces new proteins, and synthesizes new organelles.
S Phase: DNA replication occurs.
G2 Phase: cell continues growing; makes necessary organelles and molecules for DNA replication.
M Phase: cell division stage encompassing prophase, metaphase, anaphase, and telophase.

Mitosis

Prophase: Chromosomes condense, spindle fibers form, and the nuclear membrane breaks down.
Metaphase: Chromosomes line up along the middle of the cell.
Anaphase: Sister chromatids separate and move to opposite poles of the cell.
Telophase: Chromosomes decondense, spindle fibers break down, and nuclear membranes reform.

Meiosis

A process that creates gametes (sex cells).
Establish 4 gametes from one initial cell.
Generates genetic diversity through crossing over and independent assortment.
Oogenesis creates eggs; spermatogenesis creates sperm.
Homologous pairs of chromosomes line up, undergo crossing over (exchanging segments), and separate in meiosis I and later the sister chromatids separate in meiosis II to create 4 unique haploid cells.

Regulating the Cell Cycle

The cell cycle is controlled by internal and external regulators.
There are specific proteins involved in this process, including cyclins which regulate mitosis.
Internal regulators monitor internal conditions before advancing to the next phase, ensuring a smooth cycle.
External regulators signal the cell to start or stop dividing in response to external factors such as wound healing.
Apoptosis is a programmed cell death that is important for development and maintaining healthy tissues.

Cancer

Cancer is caused by uncontrolled or unregulated cell growth.
Cancer cells ignore normal regulatory signals.
Cancer cells can form tumors.
Benign tumors do not spread—malignant tumors can spread to other parts of the body.
Carcinogens are substances known to cause cancer.

Cancer Treatments

There are various treatments, such as surgery, radiation, chemotherapy, and immunotherapy.
These methods aim to eliminate cancer cells by various means including targeting DNA, or by boosting the body's own immune system to fight the cancer cells.

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Description

Explore the concepts of cell size, efficiency, and division in this quiz. Learn how surface area to volume ratios affect cellular function and the implications of asexual reproduction. Test your knowledge on how cells manage their processes and the importance of maintaining efficient material exchange.