Question

Which of the following is a true statement? (A) The dragonflies are producers, the phytoplankton are primary consumers, and the snakes are tertiary consumers. (B) The phytoplankton are producers, the dragonflies are primary consumers, and the snakes are tertiary consumers. (C) The phytoplankton are producers, the snakes are primary consumers, and the dragonflies are tertiary consumers. (D) The snakes are producers, the dragonflies are primary consumers, and the phytoplankton are tertiary consumers.

Short answer

The correct statement is (B) The phytoplankton are producers, the dragonflies are primary consumers, and the snakes are tertiary consumers.

Step-by-step solution

Identify the producer

First, we need to identify the producer among the dragonflies, phytoplankton, and snakes. Producers are organisms that create their own food through the process of photosynthesis. Phytoplankton are photosynthetic organisms found in the water, while dragonflies and snakes are not. Therefore, the phytoplankton are the producers in this scenario.

Identify the primary consumer

Next, we need to determine which organism is the primary consumer, i.e., the organism that eats the producer. Dragonflies are insects that feed on other insects and small creatures, such as the phytoplankton. Snakes are reptiles that feed on other animals such as rodents, birds, and sometimes insects, but not on producers such as phytoplankton. Based on this information, the primary consumer is the dragonfly.

Identify the tertiary consumer

Finally, we have to recognize the tertiary consumer - the organism that eats secondary consumers. Snakes are known to consume various animals, including insects like dragonflies, which in this scenario would be considered secondary consumers since they eat phytoplankton, the producer. Based on their diet, snakes are the tertiary consumers in this food chain.

Select the correct statement

With the identified roles of each organism in the food chain, we can now choose the correct statement: (A) The dragonflies are producers, the phytoplankton are primary consumers, and the snakes are tertiary consumers. (False) (B) The phytoplankton are producers, the dragonflies are primary consumers, and the snakes are tertiary consumers. (True) (C) The phytoplankton are producers, the snakes are primary consumers, and the dragonflies are tertiary consumers. (False) (D) The snakes are producers, the dragonflies are primary consumers, and the phytoplankton are tertiary consumers. (False) The correct statement is (B) The phytoplankton are producers, the dragonflies are primary consumers, and the snakes are tertiary consumers.

Key concepts

Producers and Consumers in Ecology

Understanding the roles of producers and consumers is essential in studying ecology. Producers, or autotrophs, are organisms that can create their own food from inorganic substances - usually through the process of photosynthesis. They form the basis of every food chain, providing energy for all other organisms, called consumers.

Consumers are divided into several categories based on their diet: primary consumers eat producers; secondary consumers eat primary consumers and tertiary consumers eat secondary consumers.

In a given ecosystem, a dragonfly might typically act as a primary consumer, while a snake would be a tertiary consumer, as it preys on other animal consumers such as insects, birds, and small mammals.

Trophic Levels

The term trophic levels refers to the hierarchical levels in an ecosystem, occupied by organisms based on their position in the food chain. At the bottom are producers, like phytoplankton in aquatic ecosystems, which use sunlight and simple substances to create organic material through photosynthesis.

These levels move upward to primary, secondary, and tertiary consumers. Each level represents a step in the transfer of energy and nutrients as one organism is consumed by another. The efficiency of this energy transfer is low, which is why there are fewer organisms at higher trophic levels.

Key Points of Trophic Levels

• Primary consumers are often herbivores.
• Secondary consumers are carnivores or omnivores that consume herbivores.
• Tertiary consumers, like snakes, are typically apex predators.

Photosynthesis

Photosynthesis is the biochemical process by which producers, such as plants, algae, and some bacteria, convert light energy, usually from the sun, into chemical energy; this is stored as glucose and serves as food for the organism itself and for consumers within an ecosystem.

The general equation for photosynthesis is: \[6CO_2 + 6H_2O + light energy \rightarrow C_6H_{12}O_6 + 6O_2.\] This process is fundamental to life on Earth as it underpins the energy flow through ecosystems and is the source of oxygen in the atmosphere.

Ecosystems

An ecosystem encompasses all living organisms, such as animals, plants, and microbes, in a particular area, interacting with each other and their non-living environments. These relationships form complex networks of food webs, which are combinations of different food chains.

An ecosystem's health and stability depend on its biodiversity and the balance of energy flow between producers, consumers, and decomposers. Disruptions to this balance, such as the removal of a key species, can have cascading effects on the ecosystem.

Components of Ecosystems

• Abiotic factors: non-living elements like climate, water, nutrients.
• Biotic factors: living components like plants, animals, and bacteria.
• Nutrient cycles: processes that recycle elements like carbon and nitrogen.