Question

A student creates a model of a closed ecosystem by filling a glass tank half

full with water, then adding 10 snails and two small aquatic plants. The next
day, all the snails are dead. What is the most likely cause of their death?
A. The rates of cellular respiration and photosynthesis in the tank
were both too high.
B. The rates of cellular respiration and photosynthesis in the tank
were both too low.
O C. The rate of cellular respiration in the tank was much higher than
the rate of photosynthesis.
D. The rate of photosynthesis in the tank was much higher than the
rate of cellular respiration.
SUBMIT
e
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Answer 1

1. Snails carry out respiration only

2. Aquatic plants carry out both respiration and photosynthesis Although the aquatic plants can absorb carbon dioxide and release oxygen through photosynthesis, the amount of snail is much more than that of the aquatic plants.

During night time,the absence of light prevent the plants from carrying out photosynthesis. No oxygen is released at this time. There is a net release of carbon dioxide in the closed system and hence the snail died of suffocation.

Answer 2

C. The rate of cellular respiration in the tank was much higher than

the rate of photosynthesis

Step-by-step explanation:

In nature, cellular respiration and photosynthesis are opposite metabolic reactions. Cellular respiration, which is the process of releasing energy, requires oxygen while photosynthesis, which is the process of manufacturing foods by green plants, releases oxygen into the atmosphere. The two equations are as follows:

Photosynthesis:

6CO2 + 6H2O → C6H1206 + 6O2 (oxygen released)

Respiration:

C6H1206 + 6O2 (oxygen used) → 6CO2 + 6H2O

According to this question, 10 snails and two small aquatic plants were added to a closed glass tank half full with water. It was observed that all the snails died. This is most likely due to the fact that the rate of cellular respiration in the tank was much higher than the rate of photosynthesis.

In other words, the usage of oxygen via cellular respiration was much higher than the release of oxygen via photosynthesis.