A population of bacteria is initially 1800 cells. After 2 hours, the population has increased to 1900 cells. Assume that the population is an exponential function of time. How many hours after the start will the instantaneous growth rate of the population be 200 cells per hour

The instantaneous growth rate of the bacteria will be 200 cells per hour after 3 hours.

Explanation:

There are four phases of bacterial growth represented by a bacterial growth curve, and they are; the lag phase, the log/exponential phase, the stationary phase, and the decline phase.

Under favorable conditions of nutrients, temperature, pH, oxygen and space, bacterial cells grow at a geometric or exponential rate this is the log phase, this means that the population doubles after a regular interval of time. In order to determine the time to attain a growth rate of 200 cells per hour, we have to start from the growth rate at 1 hour from the start and work upwards, and this is calculated thus;

it was given that after 2 hours, the population increased from 1800 to 1900, meaning that after 2 hours the growth rate was 100 cells per hour

∴ 0 to 2 hours = 100 cells/hour

2 hours = 100 cells/hour

∴ 1 hour = 100/2 = 50 cells/hour.

After the first hour, the growth rate was 50 cells/hour. Remembering that exponential growth is doubling of a population at an equal time interval (1 hour)

1 hour = 50 cells/hour

2 hours = 50 + 50 = 100 cells/hour

3 hours = 100 + 100 = 200 cells/ hour

4 hours = 200 + 200 = 400 cells/hour

This continues until the bacteria reaches the stationary phase of the growth curve then begins to decline.

so from the calculation above, at 3 hours the growth rate is 200 cells per hour.

I suggest you read up bacterial growth phases for better understanding.

answer: angiosperms

dicots

angiosperms are highly evolved plants, they produce seeds which are enclosed within in a carple. these are the largest group of plants on earth. they include trees, shrubs, herbs and small flowering plants. angiosperms exhibit a flowering stage in their life cycle. the flower serves the function of reproduction and fruit formation in majority of angiosperms. dicot is the term used to describe flowering plants that have two seed leaves. dicots are plants which develop seeds which split into two parts called cotyledons. each cotyledon contains one embryo.

here, a small purple flower development indicates that the plant belongs to angiosperms and having two embryonic leaves indicates it belongs to dicots.  

the answer is c on e2020, bud.