To perform this test to check if gold is real, make a light, tiny scratch on the item using a small nail file. Choose a spot that is not noticeable if possible. Use a dropper to apply a small drop of nitric acid to the scratch. If there is no reaction, then the piece is probably made from real gold.
Answer:
phytoplankton
Explanation:
Phytoplankton can be defined as a set of photosynthesizing microorganisms that live floating on the water surface. It is composed of microscopic algae and cyanobacteria, which can be unicellular, colonial or filamentous. These microorganisms are defined as the primary producers of an ocean grazing food network.
Because phytoplankton live in aquatic environments - both in limic (eg lakes) and marine environments - they have a number of adaptations that guarantee their survival in the water column. Some of these microorganisms, for example, have flagella that aid locomotion; others, in turn, have gas vacuoles that aid in flotation, while some of them have mucilage, which surrounds the cells and ensures protection, flotation and locomotion.
Answer: Local chemical conditions
Explanation: A Precapillary Sphincter is a smooth muscle that is located in circles around the capillaries.
The precapillary sphincter helps to coordinate blood flow to the into the capillaries by causing the capillaries to decrease the flow of blood to tissues that are dormant or not active.
Organisms that originated in a certain geographic region and can only be found in that region are said to be endemic.
Explanation:
Endemic organisms are taxonomic species (plants and animals) which originates and distributed only in specific geographic regions. This state of evolution is called endemism.
They are said to be native or indigenous to that particular region which can be an ecological habitat, an entire nation, an island, a mountain range etc. Certain parts are known for majority of their species being endemic like St. Helen Island, New Caledonia Island, Hawaiian Islands, Southern regions of Africa, and Australia.
The species becomes endemic to a particular region because of the presence of certain bio-geographical environmental qualities of that habitat which are favorable to that species.
When these conditions become unfavorable, then species becomes restricted leading to endangerment or extinction of the species.
Examples:
- Kangaroo - Australia
- Nilgiri Tahr, - Nilgiri Hills, India
- The Redwood trees of West Coast of the USA
- Plants like kalo, sumac of Hawaii
