Answer:
a. Centromere
A centromere is a specialised DNA sequence of a chromosome that links pair of sister chromarids (a dyad)
Answer:
To summarize what we know to this point, the cellular process of transcription generates messenger RNA (mRNA), a mobile molecular copy of one or more genes with an alphabet of A, C, G, and uracil (U). Translation of the mRNA template converts nucleotide-based genetic information into a protein product. Protein sequences consist of 20 commonly occurring amino acids; therefore, it can be said that the protein alphabet consists of 20 letters. Each amino acid is defined by a three-nucleotide sequence called the triplet codon
The moon revolves around the Earth as a natural satellite.
Answer: Imagine life without your best friend. Who would you hang out with and talk to about your problems? Life would be so lonely! You rely on your friends for companionship, fun, and support. Animals rely on each other, too. Some have lifelong relationships with other organisms, called symbiotic relationships. There are three different types of symbiotic relationships: mutualism, commensalism, and parasitism.
Mutualism: both partners benefit. An example of mutualism is the relationship between the Egyptian plover and the crocodile. In the tropical regions of Africa, the crocodile lies with its mouth open. The plover flies into its mouth and feeds on bits of decaying meat stuck in the crocodile’s teeth. The crocodile does not eat the plover. Instead, he appreciates the dental work. The plover eats a meal and the crocodile gets his teeth cleaned. Coincidentally, the Egyptian plover is also known as the crocodile bird.
Commensalism: only one species benefits while the other is neither helped nor harmed. For example, remora fish are very bony and have a dorsal fin (the fin on the back of fish) that acts like a suction cup. Remora fish use this fin to attach themselves to whales, sharks, or rays and eat the scraps their hosts leave behind. The remora fish gets a meal, while its host gets nothing. Selfish, sure, but neither gets hurt.
Parasitism: One organism (the parasite) gains, while the other (the host) suffers. The deer tick is a parasite. It attaches to a warmblooded animal and feeds on its blood. Ticks need blood at every stage of their life cycle. They also carry Lyme disease, an illness that can cause joint damage, heart complications, and kidney problems. The tick benefits from eating the animal's blood. Unfortunately, the animal suffers from the loss of blood and nutrients and may get sick.
