B2 Cell Division AQA

What molecule carries genetic information within a chromosome?

DNA (Deoxyribonucleic acid).

What is the name for a section of a chromosome that codes for a specific protein?

A gene.

How many total chromosomes are found in a normal human body cell?

46 chromosomes.

Human body cells contain chromosomes arranged into how many pairs?

23 pairs.

What is the sex chromosome combination for a biological female?

XX

What is the sex chromosome combination for a biological male?

XY.

The series of steps a cell goes through as it grows and divides is known as the _____.

Cell cycle

Which stage of the cell cycle is the longest?

Interphase.

During interphase, what happens to the cell's genetic material before division?

The DNA replicates to form two copies of each chromosome.

What happens to the number of sub-cellular structures, such as ribosomes, during interphase?

They increase in number.

Why must a cell increase its number of mitochondria before dividing?

To provide the energy required for cell growth and protein synthesis.

What is the specific role of ribosomes in the growth of new daughter cells?

They are the site of protein synthesis.

The process by which a parent cell divides into two genetically identical daughter cells is called _____.

Mitosis

In which stage of the cell cycle is a complete set of chromosomes pulled to each end of the cell?

Mitosis.

What is the outcome of mitosis in terms of the number of nuclei?

The nucleus divides to form two nuclei.

During mitosis, where do the chromosomes line up to ensure an even split?

The equator (middle) of the cell.

To which part of the cell do chromosomes travel after they separate during mitosis?

The opposite poles.

What is the name for the individual 'arms' of a duplicated chromosome?

Chromatids.

The final stage of the cell cycle, where the cytoplasm and cell membrane physically divide, is called _____.

Cytokinesis

What is the relationship between the DNA of the parent cell and the two daughter cells produced by mitosis?

They are genetically identical.

List three biological functions that require mitosis.

Growth, repair of damaged tissues, and asexual reproduction.

How does mitosis contribute to the repair of a wound?

It produces new cells to replace those that were lost or damaged.

What term describes an undifferentiated cell capable of becoming one or more types of specialised cell?

A stem cell.

Where are embryonic stem cells typically sourced for research?

Early human embryos (often spare embryos from fertility clinics).

What is the differentiation potential of an embryonic stem cell?

It can differentiate into any type of specialised cell in the body.

Where in the human body can adult stem cells be found?

Bone marrow.

How does the differentiation potential of adult stem cells compare to embryonic stem cells?

Adult stem cells can only differentiate into certain types of cells (e.g., blood cells).

What is a major ethical disadvantage of using embryonic stem cells?

The embryo is destroyed, which some view as a potential human life.

State one medical risk associated with treating patients with embryonic stem cells.

The risk of transferring viral infections to the patient.

What is a significant advantage of using adult stem cells over embryonic ones regarding ethics?

Adults can give informed consent for their stem cells to be used.

In therapeutic cloning, why are the produced stem cells unlikely to be rejected by the patient?

They have the same genes as the patient.

What is the first step in the process of therapeutic cloning?

Cells from a patient's body are used to create a cloned early embryo of themselves.

Where are stem cells found in plants?

Meristems (roots and shoots).

What is unique about the differentiation ability of plant meristem cells throughout the plant's life?

They retain the ability to differentiate into any type of plant cell at any point.

Why is cloning rare plant species using meristems beneficial?

It can prevent the species from going extinct.

What is a disadvantage of producing large crops of genetically identical cloned plants?

A single disease or genetic defect could destroy the entire crop.

What is the term for cell division in bacteria?

Binary fission.

Under optimum conditions, how frequently can some bacteria divide?

Every 20 minutes.

Why is the lid of a Petri dish not sealed completely when growing bacteria?

To allow oxygen in, preventing the growth of harmful anaerobic bacteria.

The process where a cell gains specific adaptations to perform a particular function is called _____.

Differentiation

What is a gamete?

A sex cell (sperm or egg) containing half the genetic information of a regular body cell.

How many chromosomes are found in a human sperm or egg cell?

23 chromosomes.

What cell is formed when two gametes fuse during fertilisation?

A zygote.

A ball of identical cells formed by the repeated mitosis of a zygote is called an _____.

Embryo

Which medical condition is commonly treated with a bone marrow transplant?

Leukaemia.

In asexual reproduction, what is the genetic relationship between the parent and the offspring?

They are genetically identical (clones).

What are the three sub-stages of interphase?

G1 (growth), S (DNA synthesis), and G2 (final preparation).

During which phase of mitosis do the sister chromatids separate and move to opposite poles?

Anaphase.

During which phase of mitosis does the nuclear envelope reform around the chromosomes?

Telophase.

In what stage of the cell cycle does the cell carry out normal metabolic functions?

Interphase G1 phase).

What occurs during the 'S' phase of the cell cycle?

DNA replication (synthesis).

What occurs during the 'G2' phase of the cell cycle?

The cell checks for DNA damage and prepares for the mitotic phase.

What structure is used to grow bacteria in a laboratory setting?

An agar gel plate or nutrient broth.

What is the primary reason for a long wait time for adult stem cell therapy?

The difficulty of finding a suitable donor.

How does cytokinesis differ between animal and plant cells?

Animal cells pinch in two via a contractile ring, while plant cells form a cell plate.

Why is mitosis essential for a multicellular organism's development from a zygote?

It allows the single cell to multiply into the millions of cells needed to form an embryo.

In plant cloning, why is it an advantage to clone plants with disease resistance?

It allows for the fast, low-cost production of large numbers of identical, healthy plants.

How does the size of a cell change during the first stage of the cell cycle?

The cell grows bigger.

What is the function of a 'micrograph' in the study of chromosomes?

It is a photograph taken of a microscopical image to see condensed chromosomes.

What happens to DNA just before a cell is ready to divide?

It copies itself, then coils and condenses into visible chromosomes.