Cell: The Unit of Life quiz

Who stated that all cells arise from pre-existing cells?

The smallest known cells are:

Ribosomes in prokaryotes are of the type:

Which organelle is called the 'suicidal bag'?

The middle lamella is mainly made of:

Which plastids store oils and fats?

The arrangement of microtubules in cilia is:

The Golgi apparatus was first observed by:

A chromosome with the centromere at the tip is:

Which of the following does not have a membrane?

Distinguish between Gram-positive and Gram-negative bacteria. (2 marks)

What are inclusion bodies in prokaryotes? (2 marks)

What is the function of the smooth endoplasmic reticulum? (2 marks)

What is the role of the tonoplast? (2 marks)

What is the function of the nucleolus? (2 marks)

What are polysomes? (2 marks)

Distinguish between cilia and flagella. (2 marks)

What is the structure of a centriole? (2 marks)

What are microbodies? (2 marks)

What are satellite chromosomes? (2 marks)

A light microscope has a 10x eyepiece and a 100x objective. An object appears 5 mm long. Calculate the actual size in micrometres. (3 marks)

The human genome of about 6.6 x 10^9 base pairs is spread over 46 chromosomes. Calculate the average number of base pairs per chromosome. (3 marks)

A spherical cell has a radius of 10 micrometres. Calculate its surface area and volume (take pi = 3.14) and its surface area to volume ratio. (3 marks)

A plant cell vacuole occupies 90% of a cell of volume 2,000 cubic micrometres. Calculate the volume of the vacuole and of the remaining cytoplasm. (3 marks)

A chloroplast is 5 micrometres long and 2 micrometres wide. How many would fit end to end across a cell 100 micrometres long? (3 marks)

Read the passage and answer the questions. A student observed onion peel and human cheek cells under a microscope. The onion cells were rectangular, with a distinct cell wall and a large central vacuole. The cheek cells were irregular in shape with no cell wall, and their nuclei stained dark with methylene blue. (i) Name two structures present in plant cells but absent in animal cells. (ii) Name one structure present in animal cells but absent in most plant cells. (iii) Why do the nuclei stain dark? (5 marks)

Read the passage and answer the questions. The endoplasmic reticulum divides the intracellular space into two distinct compartments, the luminal and extra-luminal compartments. ER often shows ribosomes attached to its outer surface. The ER bearing ribosomes on its surface is called rough ER. In the absence of ribosomes, it appears smooth and is called smooth ER. (i) What is the function of RER? (ii) Which cells have abundant RER? (iii) What is the function of SER in animal cells? (5 marks)

Read the passage and answer the questions. Mitochondria are double-membrane-bound structures, with the outer membrane and the inner membrane dividing the lumen into two aqueous compartments. The inner membrane forms a number of infoldings called cristae towards the matrix. The matrix possesses a single circular DNA molecule, a few RNA molecules, ribosomes (70S) and the components required for protein synthesis. (i) Why are mitochondria called the powerhouses of the cell? (ii) What is the role of cristae? (iii) How do mitochondria divide? (5 marks)

Read the passage and answer the questions. The nucleus as a cell organelle was first described by Robert Brown as early as 1831. Later the material of the nucleus stained by basic dyes was given the name chromatin by Flemming. The nuclear envelope has two parallel membranes with a space between them, the perinuclear space. Nuclear pores are present at many places. (i) What is the function of nuclear pores? (ii) What is chromatin made of? (iii) Name two cells without a nucleus. (5 marks)

Read the passage and answer the questions. A bacterial cell has a three-layered cell envelope. The glycocalyx may be a loose sheath called the slime layer in some, while in others it may be thick and tough, called the capsule. Many bacteria have flagella with three parts: the filament, the hook and the basal body. Pili and fimbriae are surface structures that do not play a role in motility. (i) Name the three layers of the cell envelope. (ii) What is the function of fimbriae? (iii) What are plasmids, and why are they useful? (5 marks)

Describe the development of the cell theory. Compare prokaryotic and eukaryotic cells with labelled diagrams. (6 marks)

Describe the structure of the cell membrane according to the fluid mosaic model. Explain the transport of molecules across it. (6 marks)

Describe the endomembrane system and the structure and functions of the ER, Golgi apparatus, lysosomes and vacuoles. (6 marks)

Describe the structure of mitochondria and plastids with diagrams. Explain the types of plastids and their functions. (6 marks)

Describe the structure of the nucleus and chromosomes with labelled diagrams. Classify chromosomes by the position of the centromere. (6 marks)