Answer:
Option A, keystone species
Explanation:
Keystone species are responsible for controlling any species from becoming dominant over all other species. The keystone species are found at the top of all the energy pyramids and food chains.
They control the explosion of population of prey and hence regulate the overall ecological diversity.
Some common example of keystone species is as follows –
Bison, prairie dog, large mammalian predators,
Hence, option A is correct
Out of the choices given, the conclusion that can be made is that in both cases, societies were brought into contact through trade. The cultural exchanges that went along with that trade enriched those societies. The correct answer is C.
The five kingdoms of living organisms are Monera, Protista, Fungi, Plantae and Animalia. Monera is for single-celled individuals which just absorb nutrients from the cell wall. Protista is for protists, fungi is for muticellular organisms, plantae is to plants and animalia is to animals. The common structure among them is DNA>
People sleep (usually) at night, and dogs and cats doze pretty much whenever they can. But how about other living things, like plants? Whether or not those tulips turn in at the end of the day depends on whom you ask—and how you define sleep.
Plants don’t have a central nervous system, which is an essential regulator of sleep in humans. But they do tune themselves to a 24-hour circadian rhythm, just like you. And they do shut down certain processes, like photosynthesis, when the sun goes down, shifting their focus instead to delivering glucose (sugar) throughout the plant. Some plants, including the aptly named morning glory, also close their blooms when the sun goes down.
Sunlight is a key trigger for humans to know what time to sleep and when to be awake. And the same is true of plants. While light and dark tell your body when to produce the hormone melatonin, which cues your body to feel sleepy, light and dark triggers tell plants when to produce the hormone auxin, which controls growth and development.
Plants may not be able to get up and hunt for food (or grocery shop, or call for takeout, for that matter!), but they do move in small ways to maximize their exposure to energy-giving sunlight. During the day, they soak up the sun in order to make energy through photosynthesis, a plant’s version of eating. Then, at night, they turn their attention to metabolizing the energy that they’ve taken in and using it to grow. So maybe you should be saying “goodnight” to your garden when you turn out the lights! hope this helps
