The natural selection is the survival of the fittest, which means that o<span>nly the best adapted individuals survive and reproduce, contributing the most to the next generation</span>
According to natural selection, birds such as cardinals , eagles, and ducks have differently shaped feet due to <span>adaptation to different environments and feeding habits.
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Answer:
Hormones are controlled by a
(negative)
feedback system between the glands that produce this hormone and the  concentration of blood calcium ions. If the level of ions is
(low)
,hormone secretion is increased. This causes  resorption by  cells called
which releases both calcium and phosphate ions into the blood stream.
Explanation: 
Negative Feedback a the process in your body that helps to maintain Homeostasis. If some variable changes a value in your body, like your ion levels,  your glands produce a hormone that causes resorption by  cells. This releases both calcium and phosphate ions into the blood stream and therefore your ion levels go back to normal.
Hope this helps!
 
        
             
        
        
        
Answer:
 RNA is a single-stranded nucleic acid. RNA has a ribose sugar instead of a deoxyribose sugar like DNA. RNA nucleotides have a uracil base instead of thymine. There are many different types of DNA RNA is single stranded RNA forms a double helix.
Explanation:
 
        
             
        
        
        
<h2>Availability of Plankton</h2>
Explanation:
- The term plankton comes from the Greek derivative planktos, meaning wandering. Organisms in this group spend either part or all of their life in a drifting state, with no ability to swim against a current. Most have little or no ability to swim at all. Though some are larger, most planktonic creatures are microscopic and make up the bottom of the food chain in aquatic environments
- Plankton can be divided into two categories: phytoplankton are those organisms that are plant-like, and zooplankton are organisms that are animal-like. Interestingly enough, many planktonic species are neither plant nor animal but are creatures that belong to the kingdom Protista
- Zebra muscles are found in water bodies which attached to pipes and other surfaces of water supply to impliment the availability of plankton