<span>In the past, human populations were controlled by </span>Disease and Famine
<span>The characteristics that scientists used to classify living organisms into six kingdoms include the following:
1. Cell type: living organisms are classified into prokaryotes and eukaryotes based on the presence of nucleus and distinct arrangement of the organelles in their cells.
2. Mobility: living organisms are categorized into kingdoms based on their ability or inability to move about.
3. Cell structure: the cells structure was used to divide living organisms into plants and animals. Those living organisms that have cell wall are classified as plants while those who do not have cell wall are classified as animals.
4. Number of cells: living organisms that are made up of only one cell are classified as unicellular while those with many cells are termed multi cellular.
5. Reproduction method: living organisms are classified based on whether they reproduce sexually or asexually.
6. Manner of obtaining energy: living organisms that can prouduce their own food are called autotrophs while those that can not produce their own foood are termed heterotrophs. Plants are essentially categorised as autotrophs while animals are described as heterotrophs.</span>
Secondary consumer
(In detail) A secondary consumer eats the primary consumers while the primary eats the producers. Primary consumers are herbivores while secondary consumers can be omnivores and carnivores.
