"These" should be referring to Alkali Metals.
They include metals such as Lithium, Sodium, Potassium etc.
They're classified as Group I elements because they all have one outmost shell electrons. This is why these metals are so reactive because they only need to lose one electron in order to achieve the octet of electrons (or duplet for Lithium), which means complete outmost shell electrons (2 or the 1st shell, others are 8).
The reason why they're especially reactive to Halogens (Group VII) elements are that Halogens have 7 outmost shell electrons, which only needs one more electron in order to get to the octet of electrons. So, if an Alkali metal reacts with a Halogen, the metal would give one of their electrons to the Halogen, that way, both of the elements can have an octet of electrons (or duplet).
Answer:
The correct choice is A)
There will be fewer producers in the area.
Explanation:
Very easy to deduce. A producer in biology of ecosystems is an organism that produces its own food. Another word for a producer in biology is 'autotroph'.
They produce energy directly from the energy given off by the sun or chemicals or both.
Grass (or plants) are producers. They do this with the help of water, converting solar energy into sugar or food, which are usable forms of energy.
So the more grass is consumed, the fewer producers in the area.
Cheers!
Selectively permeable means that cells only allow certain molecules to enter or exit a cell.
This pertains to the structure of proteins. Secondary structures are stabilized by the presence of hydrogen bonds. The common types of secondary structures of proteins are the alpha helix and the beta sheets, each performing different functions.
Primary structure of protein is the peptide molecule comprised of peptide bonds. Once these peptide grows long enough, it will either be arranged into alpha helices or beta sheets stabilized by hydrogen bonds and this is the secondary structure. Once there is protein folding involved in the secondary structure of protein, then the folded protein is called the tertiary structure (or a protein subunit). When protein subunits come together to perform a specific function, then that is the quaternary structure.
Attached is a figure concerning the protein structures.