# Biology Questions and Answers – Growth Models – 1

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This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Growth Models – 1”.

1. What is a sigmoid growth curve called?
a) Exponential growth curve
b) Logistic growth curve
c) Declining growth curve
d) Interacting curve

Explanation: A sigmoid growth curve is also called a logistic growth curve. It is considered to be a realistic curve. It is obtained due to the finite and limited source of resources in a population. It is also called a Verhulst-Pearl Logistic Growth curve.

2. How many phases does a logistic growth curve have?
a) 5
b) 8
c) 1
d) 4

Explanation: A logistic (sigmoidal) growth curve has 5 phases. They are lag phase, log phase, deacceleration phase, negative down acceleration phase, and stationary phase.

3. Which is the initial phase in logistic growth?
a) Log phase
b) Lag phase
c) Declining phase
d) Stationary phase

Explanation: The initial phase of logistic growth is the lag phase. It has 5 phases. It is the phase in which the population increases slowly and tends to adopt the new environment. The population density increases in the positive acceleration phase.

4. What do organisms in a population do in the lag phase?
a) Grow at a slower rate
b) Grow at a faster rate
c) Death

Explanation: The lag phase is the initial phase of a growth curve in which the population increases slowly. In this phase, the population tries to adopt the new environment. The population density increases in the positive acceleration phase.

5. Which of the following initial phase is slow?
a) Declaration phase
b) Stationary phase
c) Lag phase
d) Log phase

Explanation: The lag phase is initial and slow. It is the phase in which the population increases slowly and tends to adopt the new environment. The population density increases in the positive acceleration phase.

6. Which is the second phase of the sigmoidal growth curve?
a) Deceleration phase
b) Log phase
c) Exponential phase
d) Stationary phase

Explanation: The second phase of the sigmoid (logistic) growth curve is the log phase. It is the logarithmic, exponential growth phase in which organisms multiply at a faster rate.

7. In which of the following phase do organisms in a population multiply at a faster rate?
a) Deceleration phase
b) Stationary phase
c) Exponential phase
d) Log phase

Explanation: The organisms multiply at a faster rate in the log phase. It is the second phase of the sigmoid (logistic) growth curve. And the maximum growth of the population is observed in this phase.

8. Which is the third phase in the logistic growth curve of the population?
a) Log phase
b) Deacceleration phase
c) Lag phase
d) Negative phase

Explanation: The third phase in the logistic growth of the population is the deacceleration phase. In this phase, the organisms increase slowly. This happens due to limited resources.

9. What happens in the deacceleration phase?
a) Grow at a faster rate
c) Death
d) Organisms increase slowly

Explanation: In the deacceleration phase, the organisms increase slowly. This happens due to limited resources. It is the third phase of a sigmoid/ logistic/ S-shaped growth curve.

10. What happens in the negative down acceleration phase?
a) Grows at a faster rate
d) Death

Explanation: The negative down acceleration phase is the fourth phase of a sigmoid/ logistic/ S-shaped growth curve. In this phase the population density gradually reduces.

11. In which phase population achieves zero growth?
a) Growing phase
b) Stationary phase
c) Lag phase
d) Log phase

Explanation: The population achieves zero growth in the stationary phase. It is the last phase of logistic growth. It is due to many reasons such as exhaustion of resources, aging, etc.

12. Which letter is used to designate the carrying capacity of a population?
a) A
b) S
c) K
d) N

Explanation: The carrying capacity of a population is designated by the letter ‘K’. The resources in a given habitat can be used by the maximum possible number of a population; beyond this, no further growth is seen in a population. This is known as the carrying capacity of that species in that habitat.

13. When responses in a population are limiting which growth is observed?
a) Increasing growth
b) Logistic growth
c) Decreasing growth
d) Stationary growth

Explanation: Logistic growth is seen when resources in a population are limiting. It has 5 phases. It is also known as the sigmoid/ S-shaped growth curve. It is a more realistic growth model.

14. When responses in a population are unlimited which growth is observed?
a) Logistic growth
b) Decreasing growth
c) Lag phase growth
d) Exponential growth

Explanation: An exponential growth is observed when resources in the population are unlimited. The population grows in geometric fashion and results in a J-shaped curve.

15. Exponential growth is observed in which fashion?
a) Geometric
b) Algebraic
c) Declining 