PTS Genap Y7

Which is an example of a population?

• all the animals and plants living in a Savana

• all the plants in a desert over a period of

  10 years

• all the species of animals in wIldlife reserve

• all the edelweiss trees growing in a forest

Which of the following best describes ecology?

• The study of cells

• The study of how living things interact with their environment

• The study of evolution

• The study of heredit

A group of rabbits living in a forest is an example of a:

•  Community

• Population

• Ecosystem

• Biome

An animal's natural home, including its food and shelter, is its:

• Niche

• Habitat

• Species

• Population

In a food chain, which organism produces its own food from sunlight and inorganic materials?

• Consumer

• Decomposer

• Producer

• Predator

Which organism breaks down dead organisms and returns nutrients to the environment?

• Producer

• Consumer

• Decomposer

• Predator

If there are too many herbivores in an ecosystem and not enough producers, what might happen?

• The herbivores will find new food sources

• The producers will grow faster

• The decomposers will benefit

• Shifting ecosystem equilibrium

Decomposers are important because they :

• Compete with producers for resources

• Break down dead organisms and return nutrients to the environment

• Prey on other organisms

• Fix nitrogen from the atmospher

Which statement is FALSE about food chains?

• They show the flow of energy in an ecosystem

• Producers are always plants

• They can be connected to form food webs

• mostly prime consumer is herbivore

Answer explanation

While plants are the most common type of producer, it's not entirely accurate to say that all producers are plants. Here's a more nuanced view:

Most producers are indeed plants: The vast majority of producers are autotrophs, organisms that can synthesize their own food using sunlight, water, and inorganic nutrients. Plants, through the process of photosynthesis, are the primary example of this, forming the base of most food chains.

Some exceptions exist: However, there are other types of organisms classified as producers that aren't plants:

• Chemosynthetic bacteria: These bacteria utilize chemical energy from inorganic compounds, like hydrogen sulfide or methane, to synthesize organic molecules for growth. They are found in unique environments like hydrothermal vents and contribute significantly to deep-sea ecosystems.

• Some protists: Certain protists, like phytoplankton in the ocean, are also autotrophic and use photosynthesis to produce food. They play a crucial role in marine food webs.

An increase in the number of producers in an ecosystem can potentially lead to an increase in the population of:

• Only decomposers

• Only consumers

• Both consumers and decomposers

• Neither consumers nor decomposers

Answer explanation

An increase in the number of producers in an ecosystem can indeed lead to an increase in the population of decomposers and consumers, and here's why:

Energy flow in ecosystems: Ecosystems function through the transfer of energy, typically depicted in food chains or food webs. Producers, at the base of the food chain, capture energy from sunlight (or chemicals for chemosynthetic bacteria) and convert it into organic molecules through photosynthesis or chemosynthesis.

More food, more consumers: When there are more producers, it translates to a greater abundance of available food (plants or organic matter produced by chemosynthetic bacteria). This increase in food resources can support a larger population of consumers (herbivores that eat plants or other animals that eat herbivores).

Fueling decomposers: As consumer populations grow and feed on the increased plant matter, they inevitably produce waste products and eventually die. This dead organic matter becomes a food source for decomposers, such as fungi and bacteria. These decomposers break down the dead plants and animals, returning nutrients back into the soil, making them available for producers to utilize again.

A ripple effect: The rise in producer population creates a domino effect. More food for consumers leads to a rise in their numbers. This, in turn, provides more organic matter for decomposers, allowing their populations to flourish as well.

Carrying capacity: It's important to remember that this increase has limits. Ecosystems have a finite carrying capacity, which is the maximum number of organisms a particular environment can support. As decomposer and consumer populations rise, they will eventually reach a point where the available resources become limited again, regulating their growth.

Overall, an increase in producers creates a more abundant ecosystem that can sustain larger populations of consumers and decomposers, all playing crucial roles in the flow of energy and recycling of nutrients.