D.
variable-ratio schedule of reinforcement.
Answer:
haploid/diploid
Explanation:
The number of chromosomes can also be expressed as <em>haploid or diploid</em>, instead of 1n for one copy and 2n for two copies.
The <u>haploid number of chromosomes also refers to a copy of the chromosomes or half of the genome of organisms</u> while <u>the diploid number of chromosomes refers to the double or complete set of chromosomes in the genome of organisms. </u>
So, in other words: n = haploid and 2n - diploid.
Amino acids are the building blocks of protein. There are 20 amino acids that is present in our body where nine of them are an important component in your diet because they are not produced by the cells in the body. These are <span>leucine,</span> histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
The correct answer is a eukaryote. While it would be an impulse to answer prokaryote since the first thing that will come to our minds if we deal with a microorganism that thrives in extreme environments (i.e. hot thermal vents) will be archea, which are prokaryotes. But in this case, it is clearly specified that the single-celled organism has a nucleus which is the characteristic feature of eukaryotes.
Bacteria is incorrect as bacteria are prokaryotes. Plant is incorrect as all plants are multicellular organisms.
All living organisms are made of only 20 different aminoacids- this is the correct answer! This means that the genetic code only codes for those 20 aminoacids (for example Glutamine and Lysine).
The 20 aminoacids that can form proteins are also called Proteinogenic amino acids.
