Plant and Animal Growth Mechanisms

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are the two phases of growth discussed in animals?

Embryonic and Juvenile (correct)

Fetal and Embryonic

Adult and Zygotic

Juvenile and Adult

Where does cell proliferation continue in animals during the juvenile phase?

In the heart tissues

In the growth plates of bones (correct)

In the skin layers

In the brain regions

What is the primary region for cell proliferation in plants?

Vascular bundles

Xylem tissue

Meristems (correct)

Phloem regions

What changes occur to daughter cells formed by division at the apical meristem?

Some remain in the meristem to continue dividing. Signup and view all the answers

What is the role of the root apical meristem?

To generate cells for lengthening the root Signup and view all the answers

During which phase of life is there a rapid increase in height due to cell division in bones?

Childhood Signup and view all the answers

What happens to cells that form the margin of the meristem?

They cease divisions and differentiate Signup and view all the answers

Which of the following is NOT a characteristic of apical meristems?

They contribute to secondary growth in thickness. Signup and view all the answers

What typically happens to a haploid cell that lacks essential chromosome 21?

It leads to the death of the haploid cell. Signup and view all the answers

What is the consequence of having an extra chromosome in a haploid cell?

It usually leads to the death of the cell. Signup and view all the answers

What role do shoot apical meristems play in plant growth?

They generate cells for both stem extension and leaf development. Signup and view all the answers

What happens to cells as they travel towards the skin surface in the epidermis?

They produce keratin and become flattened and dead. Signup and view all the answers

In which scenario might an extra chromosome not be lethal?

In the case of chromosome 21 in specific individuals. Signup and view all the answers

What occurs during the fusion of gametes in relation to chromosome 21?

It may lead to a zygote that has three copies of chromosome 21. Signup and view all the answers

Why is cell replacement in the epidermis considered debatable regarding cell proliferation?

Cell death happens at a faster rate than cell division. Signup and view all the answers

What role do genes coding for essential polypeptides play in haploid cells?

They are necessary for the cell's viability. Signup and view all the answers

What is essential for tissue repair after a wound occurs in plant roots?

The presence of undifferentiated stem cells. Signup and view all the answers

How is non-disjunction related to chromosome 21 and haploid cells?

It can cause lethal conditions in haploid cells. Signup and view all the answers

How does friction affect the cells in the epidermis over time?

It causes flattened cells to be rubbed off. Signup and view all the answers

What characteristic of keratin affects epidermal cells?

It causes the cells to dry out. Signup and view all the answers

What is the expected outcome of an embryo with three copies of chromosome 21?

It is likely to lead to the death of the embryo. Signup and view all the answers

What happens to haploid cells that cannot properly undergo meiotic division?

They can die due to chromosomal abnormalities. Signup and view all the answers

Which process accompanies cell proliferation in the epidermis?

Cell differentiation and specialization. Signup and view all the answers

In what scenario might the ability of tissues to heal vary?

Based on the amount of stem cells present. Signup and view all the answers

What is the role of cohesin loops during mitosis?

They hold identical pairs of DNA molecules together. Signup and view all the answers

Which phase follows the replication of DNA in the cell cycle?

G2 phase Signup and view all the answers

What happens to cells produced by mitosis and cytokinesis when they enter G0 phase?

They stop growing and differentiate. Signup and view all the answers

How many DNA molecules are present in a chromosome during G2 phase?

Two Signup and view all the answers

In which stage of the cell cycle do cells enter Gap zero (G0)?

After cytokinesis Signup and view all the answers

What is the primary reason for cells to leave the cell cycle and enter G0?

To grow and differentiate for a specific role Signup and view all the answers

During which stage is the amount of DNA measured in cells from different cultures?

Prophase of mitosis Signup and view all the answers

What is likely to be true about the DNA content in human egg and sperm cells?

They contain a haploid amount of DNA. Signup and view all the answers

Where are ribosomes assembled in a cell?

Nucleolus Signup and view all the answers

What characterizes interphase in most cells?

High levels of protein biosynthesis Signup and view all the answers

What is the role of cyclins in the cell cycle?

To coordinate the sequence of changes Signup and view all the answers

What happens if cyclins do not reach a threshold concentration?

Cell arrests at checkpoints Signup and view all the answers

Which cyclin is responsible for preparing the cell for DNA replication?

Cyclin E Signup and view all the answers

What is one function of Cyclin B during the cell cycle?

Promotes assembly of the mitotic spindle Signup and view all the answers

What is the primary purpose of checkpoints in the cell cycle?

To prevent cells from entering mitosis prematurely Signup and view all the answers

During which phase does Cyclin D trigger the cell to enter DNA synthesis (S phase)?

G1 phase Signup and view all the answers

What characterizes malignant tumours?

They can cause cancer and often lead to multiple secondary tumours. Signup and view all the answers

Which tissues are more likely to produce malignant tumours?

Breast, ovaries, testes, and thyroid gland. Signup and view all the answers

How would you describe the variable rate of cell division in tumours?

Some tumours can grow slowly, affecting treatment options. Signup and view all the answers

What is the mitotic index?

The ratio of cells in mitosis to the total number of cells observed. Signup and view all the answers

What are the steps to calculate the mitotic index from a micrograph?

Count the number of cells in mitosis and then divide by the total number of cells. Signup and view all the answers

What imaging method is used to check for the spread of cancer?

MRI scan. Signup and view all the answers

What is commonly known as cancer?

Malignant tumours that spread. Signup and view all the answers

Why is a diagnosis of cancer always concerning for patients?

Malignant tumours can lead to serious health complications. Signup and view all the answers

Study Notes

Cell Cycle

The cell cycle is a repeating sequence of processes
Mitosis involves dividing the nucleus
Cytokinesis involves dividing the entire cell

Mitosis Stages

Prophase: Nucleus membrane disperses. Chromatids condense.
Metaphase: Chromosomes line up in the center of the cell.
Anaphase: Chromatids separate and move to opposite poles.
Telophase: Nuclear membranes reform. Chromosomes uncoil.

Meiosis

A type of cell division that produces haploid cells
Two rounds of division (meiosis I and meiosis II)
Meiosis I: Homologous chromosomes separate
Meiosis II: Sister chromatids separate

Meiosis and Variation

Crossing over: Exchange of genetic material between homologous chromosomes
Random orientation: Random alignment of homologous chromosomes
These processes create genetic variation in offspring

Cell Proliferation

Rapid increase in cell numbers
Essential for growth, cell replacement, and tissue repair
Cell division rates must be faster than cell death rates

Cell Cycle Checkpoints

Critical control points that regulate progression through the cell cycle
Ensure proper DNA replication and cell division

Mutations and Tumors

Proto-oncogenes: Involved in cell growth and division; mutations can cause them to become oncogenes (promote excessive cell division)
Tumor suppressor genes: Involved in preventing uncontrolled cell division; mutations can affect the function of these genes, causing them to lose their ability to inhibit growth
Mutations in genes that control the cell cycle can lead to uncontrolled cell growth and formation of tumors.
Mutagens increase the chance of mutations. Some chemicals and types of radiation are mutagens.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the phases of growth in animals and plants, highlighting key concepts such as cell proliferation in different regions. Test your understanding of apical meristems, haploid cells, and the processes involved in growth and division.