Cell division, cell diversity and cellular organisation

Question 1

What is the cell cycle?

Answer 1

The sequence of events that takes place in a cell leading to its division and replication.

Question 2

What are the main stages of the cell cycle?

Answer 2

Interphase (G1, S, G2), mitosis, and cytokinesis.

Question 3

What happens during G1 phase?

Answer 3

Cell grows, organelles replicate, and proteins are synthesised.

Question 4

What happens during S phase?

Answer 4

DNA is replicated.

Question 5

What happens during G2 phase?

Answer 5

Cell continues to grow and prepares for mitosis.

Question 6

What is mitosis?

Answer 6

A type of cell division that produces two genetically identical daughter cells.

Question 7

What happens in prophase?

Answer 7

Chromosomes condense, nuclear envelope breaks down, spindle forms.

Question 8

What happens in metaphase?

Answer 8

Chromosomes line up at the equator of the cell, attached to spindle fibres by centromeres.

Question 9

What happens in anaphase?

Answer 9

Sister chromatids are pulled apart to opposite poles.

Question 10

What happens in telophase?

Answer 10

Nuclear envelopes reform around chromosomes at each pole.

Question 11

What is cytokinesis?

Answer 11

Division of the cytoplasm to form two separate daughter cells.

Question 12

What are checkpoints in the cell cycle?

Answer 12

Control mechanisms that ensure each stage is completed properly before moving to the next.

Question 13

Where are the main checkpoints in the cell cycle?

Answer 13

G1 (before DNA replication), G2 (after DNA replication), and metaphase (during mitosis).

Question 14

What is the significance of mitosis?

Answer 14

Growth, repair, replacement, and asexual reproduction.

Question 15

What is a stem cell?

Answer 15

An undifferentiated cell capable of dividing and differentiating into various cell types.

Question 16

What is cell differentiation?

Answer 16

The process by which a cell becomes specialised for a specific function.

Question 17

What are totipotent stem cells?

Answer 17

Can form all cell types, including extraembryonic tissues (e.g., zygote).

Question 18

What are pluripotent stem cells?

Answer 18

Can form all body cells but not extraembryonic tissues.

Question 19

What are multipotent stem cells?

Answer 19

Can form a limited range of cells within a tissue type (e.g., bone marrow stem cells).

Question 20

What are sources of stem cells?

Answer 20

Embryos, adult tissue, induced pluripotent stem cells (iPSCs).

Question 21

What are erythrocytes and their function?

Answer 21

Red blood cells; transport oxygen using haemoglobin.

Question 22

What are neutrophils and their function?

Answer 22

White blood cells; engulf pathogens (phagocytosis).

Question 23

What are ciliated epithelial cells?

Answer 23

Line the airways; move mucus and trapped particles.

Question 24

What are squamous epithelial cells?

Answer 24

Flat cells that form a thin, smooth layer for rapid diffusion (e.g., alveoli).

Question 25

What are guard cells and their function?

Answer 25

Control the opening and closing of stomata in leaves to regulate gas exchange.

Question 26

What are palisade mesophyll cells?

Answer 26

Photosynthetic plant cells packed with chloroplasts.

Question 27

What is the structure and function of xylem tissue?

Answer 27

Made of dead cells with lignified walls; transports water and minerals.

Question 28

What is the structure and function of phloem tissue?

Answer 28

Made of sieve tube elements and companion cells; transports sugars and nutrients.

Question 29

What is a tissue?

Answer 29

A group of similar cells working together to perform a function.

Question 30

What is an organ?

Answer 30

A collection of tissues performing a specific function.

Question 31

What is an organ system?

Answer 31

A group of organs working together to carry out major body functions.

Question 32

What is an example of a plant organ system?

Answer 32

The transport system (xylem and phloem).

Question 33

What is an example of a human organ system?

Answer 33

The circulatory system.

Question 34

What is meiosis?

Answer 34

A type of cell division that produces four genetically different haploid cells from one diploid cell.

Question 35

Why is meiosis important?

Answer 35

It produces gametes for sexual reproduction and introduces genetic variation.

Question 36

What does diploid mean?

Answer 36

A cell with two sets of chromosomes (2n).

Question 37

What does haploid mean?

Answer 37

A cell with one set of chromosomes (n).

Question 38

How many divisions occur in meiosis?

Answer 38

Two – meiosis I and meiosis II.

Question 39

What happens during prophase I?

Answer 39

Chromosomes condense, homologous chromosomes pair up (bivalents), crossing over occurs.

Question 40

What happens during metaphase I?

Answer 40

Bivalents align at the equator, independent assortment occurs.

Question 41

What happens during anaphase I?

Answer 41

Homologous chromosomes are pulled to opposite poles.

Question 42

What happens during telophase I?

Answer 42

Two haploid nuclei form, each with half the original chromosome number.

Question 43

What happens during prophase II?

Answer 43

Chromosomes condense again in the two haploid cells.

Question 44

What happens during metaphase II?

Answer 44

Chromosomes align at the equator in each haploid cell.

Question 45

What happens during anaphase II?

Answer 45

Sister chromatids are pulled apart to opposite poles.

Question 46

What happens during telophase II?

Answer 46

Four haploid daughter cells form, each genetically unique.

Question 47

What is crossing over?

Answer 47

Exchange of genetic material between chromatids of homologous chromosomes in prophase I.

Question 48

What is independent assortment?

Answer 48

Random arrangement of homologous chromosomes in metaphase I and II.

Question 49

How does meiosis create genetic variation?

Answer 49

Through crossing over and independent assortment.

Question 50

How does meiosis differ from mitosis?

Answer 50

Meiosis produces four haploid, genetically different cells; mitosis produces two diploid, identical cells.

Question 51

In what type of cells does meiosis occur?

Answer 51

In germ cells to produce gametes.

Question 52

What is a bivalent?

Answer 52

A pair of homologous chromosomes joined together during prophase I.

Question 53

What is a chiasma?

Answer 53

The point where chromatids cross over and exchange genetic material.