1. Air quality – The higher the population in a city the higher the chances of reduced air quality due to increase per capita emissions.
2. Water usage – The higher the population density in a city, the harder it is to supply adequate clean water to everybody and the water quality may begin to drop
3. Waste management- Pollution begins to become a problem when the population in a city goes beyond its carrying capacity.
4. Land use – Urban sprawl becomes a problem when a high proportion of the city’s population is squeezed in a small portions of land
Answer:
The answer is - Although their cell structures are very different, archaean and eukaryotic cells are more closely related to each other than to bacteria, as evidenced by the fact that Bacteria was the first domain to split from the shared ancestor of Archaea and Eukarya.
Explanation:
The options are:
A. Bacterial and eukaryotic cells are more closely related to each other than to archaeans, as evidenced by the fact that bacteria and eukaryotes do not inhabit the most extreme environments.
B. Although their cell structures are very different, archaean and eukaryotic cells are more closely related to each other than to bacteria, as evidenced by the fact that Bacteria was the first domain to split from the shared ancestor of Archaea and Eukarya.
C. Bacteria and archaeans are more closely related to each other than to eukaryotes, as evidenced by their cell structures. Bacteria and archaeans are prokaryotic, while all eukaryotic cells contain mitochondria and other membrane-bound organelles.
D. The three domains of life are equally divergent from one another, so no two domains are more closely related to each other. This is supported by the evolutionary tree of life because three branches extend from one node millions of years ago.
The answer is - B. Although their cell structures are very different, archaean and eukaryotic cells are more closely related to each other than to bacteria, as evidenced by the fact that Bacteria was the first domain to split from the shared ancestor of Archaea and Eukarya.
Archaea and bacteria are similar in terms of cellular organisation and size but are however similar to eukaryotes (eukarya) at the molecular level. Archaea and Eukaryotes both undergo DNA replication and protein synthesis the same mechanism. Both of them posses closely related genes and several metabolic pathways, including the enzymes in transcription and translation.
Answer:
Answer is B. Priapism.
Explanation:
Corpus spongiosum are the three cylinders encased in the bucks fascia. They run through the glass and shaft of the penis, and during erection, they contain almost 85-90% of theology volume.
Priapism can be described as persistent erection of the penis, which is caused by excessive blood flow to the penis or when blood is trapped inside the penis blood chambers I. e, corpus spongiosum.
Priapism can be of two types, they are
1. High- flow Priapism : this is caused when the artery supplying blood to the penis is damaged, thereby, causing it to be oversupplied with oxygenated blood. This type is not painful and can be treated by adopting cold therapy, the use of ice packs.
2. Low-flow Priapism : This occurs when old blood is trapped inside the penis blood chambers. This type is very painful and require urgent medical attention.
Note that, the second type of priapism,low-flow priapism, is caused in the case of a sickled-cell person, because the shape of the blood cell can easily trap blood in the penis.
The "scissors" of the molecular biology are: DNA Restriction enzymes.
A restriction enzyme is a protein capable of cleaving a DNA fragment at a characteristic nucleotide sequence called a restriction site. Each restriction enzyme thus recognizes a specific site. Several hundred restriction enzymes are currently known.
Naturally present in a large number of species of bacteria, these enzymes have become important tools in genetic engineering.
The "glue" of the molecular biology are: DNA ligase
In molecular biology, DNA ligases are ligase-class enzymes that catalyze the formation of a phosphodiester bond between two segments of DNA. DNA ligases are involved in several essential cellular processes of DNA metabolism: in DNA replication, suture of Okazaki fragments, and in DNA repair and homologous recombination.
The use of these tools in molecular biology: Cloning
Molecular cloning is one of the bases of genetic engineering. It consists of inserting a DNA fragment (called insert) in an appropriate vector such as a plasmid for example. The new plasmid thus created will then be introduced into a host cell, generally the Escherichia coli bacterium. This will then be selected and multiplied to obtain a large amount of the plasmid of interest. Cloning a gene involves inserting it into a plasmid. A clone will be the bacterial transformant that contains this particular plasmid. In this case we speak of clone because all the individuals of the bacterial colony are genetically identical. Molecular cloning is thus different from reproductive cloning (creating an individual genetically identical to another but of a different age) or therapeutic cloning (making tissues from stem cells to perform transplants compatible with the recipient).
Molecular cloning requires restriction enzymes capable of cleaving the DNA, and DNA ligase capable of re-gluing the DNA fragments. Ligase was isolated for the first time from T4 bacteriophage. This enzyme is involved in the repair and replication of DNA. It can bind DNA fragments with compatible sticky ends. At higher concentration, this enzyme is also able to bind two ends of DNA as shown here. T4 DNA ligase works using ATP and Mg ++. It has an activity optimum of 16 ° C, but remains active at room temperature.
