Question

What is the name of the bacteria that are round in shape and occur in chains?
(A) Streptococci
(B) Staphylobacilli
(C) Spirillum
(D) Diplococci
(E) Bacillus

Answer 1

Hint: Bacteria are single celled organisms, which largely constitute the domain prokaryotes. They are grouped into different categories based on their morphology, cellular metabolism, habitats, internal and external cellular structures etc.

Complete answer:
Bacteria have unique structural and functional behaviours as they are well developed. They are typically many times smaller than eukaryotic cells, measuring a few micrometres. They have multiple morphological features, of which few are mentioned in the choices in the question. Now let us see the three the major types in their morphology:
Bacillus – Bacteria with rod-like structure belong to this category. Example: Actinomyces, Clostridium, Escherichia coli.
Cocci – Any bacteria spherical, round or oval in shape are called cocci. Example: Micrococcus species, Streptococcus pneumoniae.
Spirillum – As the name says, these are spiral or corkscrew-like in shape. Example: Members of genus Spirillum, Campylobacter and Helicobacter species.
Along with morphology, the arrangement of the cells also makes a difference. We know that round in shape means a cocci. So let us see the arrangement types in cocci:
Diplococci – arranged in pairs
Streptococci – arranged in chains
Tetrads – arranged in fours in two plans
Sarcinae – arranged in cuboidal structure
Staphylococci – arranged in clusters like in grapes

Thus, the name of the bacteria that are round in shape and occur in chains is (A) Streptococci.

Additional information:
Bacteria are important for the survival of many animals as well as plants because of their symbiotic relationship with them. For example, only bacteria and few archaea have the ability to synthesize a type of vitamin B called cobalamin, which is a vitamin that acts as a cofactor in DNA synthesis, amino and fatty acids metabolism. Similarly, many beneficial bacteria are a part of the human microbiota by residing in the nose, eyes, mouth, gut, skin etc. Nevertheless, not all bacteria are beneficial. There are many pathogenic bacteria as well which disrupts the normal functioning of animals and plants.

Note:
Bacteria are not limited to the morphology and arrangements mentioned above. Some exotic morphologies include serpentine, star shaped, and moustaches. The shape and size are not just for their appearance. It has its effect on the mobility, dispersion, biological functions, interaction with other organisms, stress resistance etc. of the bacteria.