cell

Question 1

What is the basic unit of life?

Answer 1

The cell

All living organisms are composed of cells, which are the fundamental structural and functional units of life.

Question 2

What are unicellular organisms?

Answer 2

Organisms composed of a single cell capable of independent existence and performing essential functions of life

Examples include bacteria and protozoa.

Question 3

What are multicellular organisms?

Answer 3

Organisms composed of many cells

Examples include humans and plants.

Question 4

Who first saw and described a live cell?

Answer 4

Antonie Von Leeuwenhoek

He is credited with the discovery of the microscopic world.

Question 5

What did Robert Brown discover?

Answer 5

The nucleus

He identified the nucleus as a key component of the cell.

Question 6

What is the cell theory?

Answer 6

1. All living organisms are composed of cells and products of cells. 2. All cells arise from pre-existing cells.

Formulated by Schleiden and Schwann, later modified by Virchow.

Question 7

What distinguishes prokaryotic cells from eukaryotic cells?

Answer 7

Prokaryotic cells lack a membrane-bound nucleus and organelles

Eukaryotic cells have a defined nucleus and various organelles.

Question 8

What is the semi-fluid matrix within a cell called?

Answer 8

Cytoplasm

Cytoplasm is where many cellular activities occur.

Question 9

What are ribosomes?

Answer 9

Non-membrane bound organelles found in all cells, responsible for protein synthesis

Ribosomes can be found in both prokaryotic and eukaryotic cells.

Question 10

What is the role of the cell membrane?

Answer 10

It is selectively permeable and regulates the transport of molecules across it

The cell membrane is crucial for maintaining homeostasis.

Question 11

Fill in the blank: The largest isolated single cell is the _______.

Answer 11

egg of an ostrich

Question 12

What are the basic shapes of bacteria?

Answer 12

• Bacillus (rod-like) * Coccus (spherical) * Vibrio (comma-shaped) * Spirillum (spiral)

These shapes help in identifying different types of bacteria.

Question 13

True or False: Prokaryotic cells have a well-defined nucleus.

Answer 13

False

Prokaryotes do not have a nucleus; their genetic material is not enclosed.

Question 14

What is the function of the cell wall?

Answer 14

Provides shape, protection, and support to the cell

It is present in plant cells, fungi, and some prokaryotes.

Question 15

What is the endomembrane system?

Answer 15

A system of membranous organelles that work together, including ER, Golgi complex, lysosomes, and vacuoles

Mitochondria and chloroplasts are not part of this system.

Question 16

What are the two types of endoplasmic reticulum?

Answer 16

• Rough endoplasmic reticulum (RER) * Smooth endoplasmic reticulum (SER)

RER is involved in protein synthesis, while SER is involved in lipid synthesis.

Question 17

What is the fluid mosaic model?

Answer 17

A model describing the structure of the cell membrane as a mosaic of various proteins embedded in a fluid phospholipid bilayer

Proposed by Singer and Nicolson.

Question 18

What are plasmids?

Answer 18

Small circular DNA molecules found in prokaryotes that can confer unique traits, such as antibiotic resistance

They are distinct from the genomic DNA.

Question 19

What is the role of mesosomes in prokaryotic cells?

Answer 19

Involved in cell wall formation, DNA replication, and increasing surface area

Mesosomes are infoldings of the plasma membrane.

Question 20

What are inclusion bodies?

Answer 20

Reserve materials stored in prokaryotic cells, not bound by membranes

Examples include phosphate granules and glycogen granules.

Question 21

What is osmosis?

Answer 21

The movement of water across a selectively permeable membrane from higher to lower concentration

Osmosis is a type of passive transport.

Question 22

Fill in the blank: The _______ is the major site for lipid synthesis in cells.

Answer 22

smooth endoplasmic reticulum

Question 23

What is the function of the Golgi complex?

Answer 23

Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles

It is part of the endomembrane system.

Question 24

What is the endoplasmic reticulum with ribosomes called?

Answer 24

Rough endoplasmic reticulum (RER)

RER is involved in protein synthesis and secretion.

Question 25

What is the function of the smooth endoplasmic reticulum (SER)?

Answer 25

Synthesis of lipids ## Footnote SER is also involved in the synthesis of lipid-like steroidal hormones in animal cells.

Question 26

Who first observed the Golgi apparatus and in what year?

Answer 26

Camillo Golgi, 1898 ## Footnote Golgi apparatus consists of flat, disc-shaped sacs called cisternae.

Question 27

What are the two faces of the Golgi apparatus called?

Answer 27

Cis face and trans face ## Footnote The cis face is the forming face, and the trans face is the maturing face.

Question 28

What are lysosomes rich in?

Answer 28

Hydrolytic enzymes (hydrolases) ## Footnote These enzymes digest carbohydrates, proteins, lipids, and nucleic acids.

Question 29

What is a vacuole and what does it contain?

Answer 29

A membrane-bound space in the cytoplasm containing water, sap, excretory products, and other materials ## Footnote In plant cells, vacuoles can occupy up to 90% of the cell's volume.

Question 30

What is the main function of mitochondria?

Answer 30

Aerobic respiration and ATP production ## Footnote Mitochondria are known as the 'power houses' of the cell.

Question 31

What are the three types of plastids?

Answer 31

Chloroplasts, chromoplasts, and leucoplasts ## Footnote Each type of plastid has distinct pigments and functions.

Question 32

What pigment do chloroplasts contain?

Answer 32

Chlorophyll ## Footnote Chlorophyll is essential for trapping light energy during photosynthesis.

Question 33

What are ribosomes composed of?

Answer 33

Ribonucleic acid (RNA) and proteins ## Footnote Eukaryotic ribosomes are 80S, while prokaryotic ribosomes are 70S.

Question 34

What is the cytoskeleton?

Answer 34

An elaborate network of filamentous protein structures ## Footnote It consists of microtubules, microfilaments, and intermediate filaments.

Question 35

What is the structural arrangement of cilia and flagella called?

Answer 35

9+2 array ## Footnote Cilia and flagella consist of nine doublets of microtubules surrounding two central microtubules.

Question 36

What is the function of centrioles?

Answer 36

Form the basal body of cilia and flagella and spindle fibers during cell division ## Footnote Centrioles lie perpendicular to each other within the centrosome.

Question 37

What does the nucleus contain?

Answer 37

Nucleoli and chromatin ## Footnote The chromatin is made of DNA and proteins and is involved in heredity.

Question 38

What is the nucleolus a site for?

Answer 38

Active ribosomal RNA synthesis ## Footnote Larger nucleoli are found in cells engaged in high levels of protein synthesis.

Question 39

What are chromosomes composed of during cell division?

Answer 39

Structured chromatin ## Footnote Chromatin consists of DNA and proteins, and chromosomes have a primary constriction called the centromere.

Question 40

What are the four types of chromosomes based on centromere position?

Answer 40

Metacentric, sub-metacentric, acrocentric, telocentric ## Footnote The position of the centromere determines the chromosome's arm lengths.

Question 41

What are microbodies?

Answer 41

Membrane-bound minute vesicles containing various enzymes ## Footnote Microbodies are present in both plant and animal cells.

Question 42

What is the primary role of the endoplasmic reticulum?

Answer 42

Transport of substances, synthesis of proteins, lipoproteins, and glycogen ## Footnote The ER includes both rough and smooth types.

Question 43

What is the structure of the nuclear envelope?

Answer 43

A double membrane structure with nuclear pores ## Footnote The nuclear envelope separates the nucleus from the cytoplasm.

Question 44

What is the function of the Golgi apparatus?

Answer 44

Packaging materials for delivery inside or outside the cell ## Footnote It modifies proteins synthesized by the ribosomes on the ER.

Question 45

What organelles in plant cells are responsible for trapping light energy essential for photosynthesis?

Answer 45

Chloroplasts ## Footnote Chloroplasts are crucial for the process of photosynthesis.

Question 46

Where do the light reactions of photosynthesis occur in chloroplasts?

Answer 46

Grana ## Footnote Grana are stacks of thylakoids within chloroplasts.

Question 47

Where do the dark reactions of photosynthesis take place in chloroplasts?

Answer 47

Stroma ## Footnote The stroma is the fluid-filled space surrounding the grana.

Question 48

What pigment do chloroplasts contain that gives them their green color?

Answer 48

Chlorophyll ## Footnote Chlorophyll is essential for capturing light energy.

Question 49

What are the other colored plastids called that may contain pigments like carotene and xanthophyll?

Answer 49

Chromoplasts ## Footnote Chromoplasts are responsible for the red, orange, and yellow colors in plants.

Question 50

What is the structure that encloses the nucleus in a cell?

Answer 50

Nuclear envelope ## Footnote The nuclear envelope consists of a double membrane.

Question 51

What is contained within the inner membrane of the nuclear envelope?

Answer 51

Nucleoplasm and chromatin material ## Footnote Nucleoplasm is the gel-like substance within the nucleus.

Question 52

True or False: The cell is the structural and functional unit of life.

Answer 52

True ## Footnote This statement highlights the importance of cells in biological systems.