Cell Theory And Organelles

Question 1

What is the first principle of cell theory?

Answer 1

All living things are made up of one or more cells.

This principle emphasizes the cellular composition of all organisms.

Question 2

What is the second principle of cell theory?

Answer 2

Cells are the most basic (smallest) unit of structure and function in all living things.

This principle highlights that while organelles exist, cells are the fundamental units.

Question 3

What is the third principle of cell theory?

Answer 3

All cells are created by pre-existing cells.

This principle involves cellular division processes such as mitosis and binary fission.

Question 4

What are the two main types of cells?

Answer 4

• Prokaryotic cells
• Eukaryotic cells

Prokaryotic examples include bacteria and archaea, while eukaryotic examples include animal, plant, and fungi cells.

Question 5

How do eukaryotic cells differ from prokaryotic cells in terms of genetic material?

Answer 5

Eukaryotic cells store their genetic material in a nucleus, whereas prokaryotes do not have a true nucleus.

In prokaryotes, genetic material is found in the cytoplasm.

Question 6

What is the main function of the nucleus in eukaryotic cells?

Answer 6

Acts as the control centre of the cell through the production of mRNA and tRNA, controlling protein synthesis.

It contains the cell’s genetic material in the form of DNA.

Question 7

What is the structure of the nucleus?

Answer 7

• Nuclear envelope
• Nucleoplasm
• Nucleolus
• Chromatin

The nuclear envelope has pores, and chromatin is the form of DNA found within the nucleoplasm.

Question 8

What is the primary function of mitochondria?

Answer 8

Produce ATP (adenosine triphosphate) in cellular respiration.

Cells that require more energy, like muscle cells, contain more mitochondria.

Question 9

What is the function of ribosomes?

Answer 9

Protein synthesis occurs here.

Ribosomes can be found free in the cytoplasm or attached to the rough endoplasmic reticulum.

Question 10

What is the role of Rough Endoplasmic Reticulum (RER)?

Answer 10

• Provides a large surface area for protein synthesis
• Provides a pathway for the transport of newly synthesized proteins to the Golgi apparatus

RER is covered with ribosomes, which are sites of protein synthesis.

Question 11

What is the main function of Smooth Endoplasmic Reticulum (SER)?

Answer 11

Synthesize lipids and steroid hormones.

SER does not have ribosomes attached.

Question 12

What does the Golgi apparatus do?

Answer 12

• Modifies proteins
• Packages proteins into vesicles
• Labels them for transport

It is involved in the final presentation and assembly of cellular products.

Question 13

What are lysosomes and their function?

Answer 13

Small spherical membrane-bound sacs containing hydrolytic enzymes that digest worn out cell parts and invading microbes.

Lysosomes are essential for cellular waste management.

Question 14

What is the structure of the cell surface membrane?

Answer 14

The cell surface membrane consists mainly of phospholipids and proteins.

The arrangement of these components is described by the fluid-mosaic model.

Question 15

What are phospholipids and their role in the cell membrane?

Answer 15

• Form a bilayer
• Allow lipid-soluble substances to enter and leave
• Prevent water-soluble substances from leaving
• Make the membrane flexible

Phospholipids have hydrophilic heads and hydrophobic tails.

Question 16

What are the two types of membrane proteins?

Answer 16

• Extrinsic proteins
• Intrinsic proteins

Extrinsic proteins are on the surface, while intrinsic proteins span the bilayer.

Question 17

What is the fluid-mosaic model?

Answer 17

Describes the cell membrane’s structure as fluid due to the movement of phospholipids and mosaic due to the varied proteins embedded within.

This model illustrates the dynamic nature of the cell membrane.

Question 18

What is the function of cholesterol in the cell membrane?

Answer 18

Stabilizes the interaction between phospholipids and prevents the membrane from becoming too fluid or flexible.

Cholesterol is vital for maintaining membrane integrity.

Question 19

Fill in the blank: The _______ is the control center of the cell.

Answer 19

nucleus

Question 20

True or False: Prokaryotic cells have a true nucleus.

Answer 20

False

Question 22

What is the definition of haploid cells?

Answer 22

Cells that contain 23 individual chromosomes.

Question 23

What is the definition of diploid cells?

Answer 23

Cells that have 23 pairs of chromosomes (46 chromosomes in total).

Question 24

Why do human cells need to divide?

Answer 24

To produce new cells for growth and replacement of old cells, and to produce gametes for sexual reproduction.

Question 25

What are somatic human cells?

Answer 25

Diploid cells containing 23 pairs of chromosomes.

Question 26

What type of cells are red blood cells?

Answer 26

They do not have a nucleus and do not contain any chromosomes.

Question 27

What are gametes?

Answer 27

Haploid sex cells such as sperm and egg cells.

Question 28

What happens during fertilization?

Answer 28

A diploid cell (zygote) is formed that contains a full set of chromosomes.

Question 29

What is chromatin?

Answer 29

The complex of DNA and proteins (histones) in the nucleus.

Question 30

What are chromosomes?

Answer 30

Coiled up lengths of DNA.

Question 31

What is the purpose of mitosis?

Answer 31

Growth of the organism and repair of damaged tissue.

Question 32

What are the stages of the cell cycle?

Answer 32

Interphase, mitosis, cytokinesis.

Question 33

What occurs during interphase?

Answer 33

The cell grows and duplicates its contents, including DNA replication.

Question 34

What occurs during the G1 phase of interphase?

Answer 34

The cell prepares for division by growing and synthesizing proteins.

Question 35

What occurs during the S phase of interphase?

Answer 35

DNA in the nucleus is replicated, forming pairs of identical sister chromatids.

Question 36

What occurs during the G2 phase of interphase?

Answer 36

The cell grows further in preparation for division.

Question 37

What is the G0 phase?

Answer 37

A resting phase where some cells stop dividing permanently or temporarily.

Question 38

What are the four stages of mitosis?

Answer 38

Prophase, metaphase, anaphase, telophase.

Question 39

What happens during prophase?

Answer 39

Chromosomes condense and become visible; the nuclear envelope breaks down.

Question 40

What happens during metaphase?

Answer 40

Chromosomes line up at the center of the cell; spindle fibers attach to each chromosome.

Question 41

What happens during anaphase?

Answer 41

Sister chromatids are pulled to opposite poles of the cell.

Question 42

What happens during telophase?

Answer 42

New nuclear envelopes form around each set of chromosomes, resulting in two identical nuclei.

Question 43

What is cytokinesis?

Answer 43

The process by which the cytoplasm divides, resulting in two daughter cells.

Question 44

What is cancer in relation to cell division?

Answer 44

Uncontrolled growth and division of cells due to damage to genes regulating mitosis and the cell cycle.

Question 45

The period of the cell cycle when a cell is not dividing is called _______.

Answer 45

Interphase

Question 46

The stage of mitosis when the chromosomes are first visible is called _______.

Answer 46

Prophase

Question 47

During prophase, the thin threads that span the cell are called _______.

Answer 47

Spindle fibres

Question 48

The stage when chromosomes arrange across the center of the cell is called _______.

Answer 48

Metaphase

Question 49

During the stage _______ in mitosis, the chromatids move to opposite ends of the cell.

Answer 49

Anaphase