Question

Why do bacterial colonies on agar plates form mounds instead of spreading as a monolayer?

a. Bacterial cells lack the ability to spread on agar surfaces.
b. Nutrient diffusion from below leads to mechanistic growth patterns.
c. Agar inhibits bacterial spreading in a monolayer.
d. Bacterial colonies naturally form mounds due to their shape.

What is the role of nutrient diffusion in the formation of bacterial colonies on agar plates?
a. Nutrients inhibit bacterial growth.
b. Nutrient diffusion does not affect bacterial colony formation.
c. Nutrient diffusion from below contributes to colony growth.
d. Nutrient diffusion only occurs at the edge of the colony.

How is the orientation of bacterial cells within a colony related to colony mounding?
a. Cell orientation has no impact on colony structure.
b. Horizontally oriented cells lead to flatter colonies.
c. Vertically oriented cells contribute to mounding.
d. Cell orientation is random and does not affect colony shape.

According to the provided figure, what does the color purple represent in the cross-sectional view of the colony?
a. Actively dividing cells
b. Cells that have not divided for the past 10 hours
c. The growth zone of the colony
d. Nutrient-rich areas in the colony

Which term is used to describe the process of bacterial colonies forming a mound due to explicit mechanical forces?
a. Nutrient diffusion
b. Verticalization
c. Colony spreading
d. Monolayer growth

Answer 1

Bacterial colonies' colonial morphology includes a range of distinct physical characteristics such as texture, transparency, color, and form, which help in identifying and differentiating bacterial species.

Step-by-step explanation:

Bacterial colonies on agar plates often show variation in colonial morphology, a term that refers to the visible characteristics of these colonies. When describing the morphology of bacteria colonies, microbiologists typically look at specific aspects like texture, transparency, color, and form, which includes size, overall shape, margin, and elevation of the colony.

The texture may be smooth, rough, or wrinkly. The transparency can range from opaque to transparent or translucent, helping to differentiate between species. Color may vary widely, and some colonies even produce pigments that can be seen on the agar. The form, or shape, also serves as an identifying feature. This includes the overall appearance of the colony's surface, the appearance of its edges or margins (whether they are smooth, irregular, lobated, etc.), and how it appears from a side view (its elevation), which could be flat, raised, or even piled into a mound.

Texture, color, and form are not only distinct but can also be influenced by the type of agar or medium used. For instance, differential growth on various media might be due to the presence or absence of certain nutrients, thus affecting colony morphology. This highlights the adaptability and diversity of bacterial species in response to their environment.