Answer:
The mitosis process includes only four phases of the event in mitotic cell division.
Explanation:
- Mitosis is the biological cell division cycle that produces tow daughter cell with equivalent number of chromosomes.
- In mitosis the nucleus divides, chromosome separates and moves to the opposite poles and forms two daughter cell at last.
- There are four phases in the mitosis cell division: prophase, metaphase, anaphase, and telophase repectively in the order.
- These four phases causes cytokinesis and occur in sequential order.
The most common aneuploidy that infants can survive with is trisomy 21, which is found in Down syndrome, affecting 1 in 800 births. Trisomy 18 (Edwards syndrome) affects 1 in 6,000 births, and trisomy 13 (Patau syndrome) affects 1 in 10,000 births.
A pathogen is a microorganism that is able to cause disease in a plant, animal or insect. Pathogenicity is the ability to produce disease in a host organism. Microbes express their pathogenicity by means of their virulence, a term which refers to the degree of pathogenicity of the microbe. Hence, the determinants of virulence of a pathogen are any of its genetic or biochemical or structural features that enable it to produce disease in a host.
The relationship between a host and a pathogen is dynamic, since each modifies the activities and functions of the other. The outcome of such a relationship depends on the virulence of the pathogen and the relative degree of resistance or susceptibility of the host, due mainly to the effectiveness of the host defense mechanisms. Staphylococcus aureus, arguably the most prevalent pathogen of humans, may cause up to one third of all bacterial diseases ranging from boils and pimples to food poisoning, to septicemia and toxic shock. Electron micrograph from Visuals Unlimited, with permission.
The Underlying Mechanisms of Bacterial Pathogenicity
Two broad qualities of pathogenic bacteria underlie the means by which they cause disease:
1. Invasiveness is the ability to invade tissues. It encompasses mechanisms for colonization (adherence and initial multiplication), production of extracellular substances which facilitate invasion (invasins) and ability to bypass or overcome host defense mechanisms.
2. Toxigenesis is the ability to produce toxins. Bacteria may produce two types of toxins called exotoxins and endotoxins. Exotoxins are released from bacterial cells and may act at tissue sites removed from the site of bacterial growth. Endotoxins are cell-associated substance. (In a classic sense, the term endotoxin refers to the lipopolysaccharide component of the outer membrane of Gram-negative bacteria). However, endotoxins may be released from growing bacterial cells and cells that are lysed as a result of effective host defense (e.g. lysozyme) or the activities of certain antibiotics (e.g. penicillins and cephalosporins). Hence, bacterial toxins, both soluble and cell-associated, may be transported by blood and lymph and cause cytotoxic effects at tissue sites remote from the original point of invasion or growth. Some bacterial toxins may also act at the site of colonization and play a role in invasion. Acid-fast stain of Mycobacterium tuberculosis, the agent of tuberculosis (TB). The bacteria are the small pink-staining rods. More than one-third of the world population is infected. The organism has caused more human deaths than any other bacterium in the history of mankind. Although its ability to produce disease is multifactorial, it is not completely understood. American Society of Microbiology, with permission.
Answer:
The correct answer is "Redwood tree; human being; Paramecium; White Blood Cell; Escherichia coli; Chickenpox virus; Ribosome; Prion fibril; Water molecule; Sulfur atom".
Explanation:
Redwood trees are gigantic trees, and its size can reach up to 90 meters.
The average size of a human being is 1.7 meters for males and 1.6 meters for females.
Paramecium are members of the protozoa genus, among the largest unicellular algae. Its average size is among 50 to 330 micrometers.
White Blood Cell are up to 17 micrometers in diameter.
Escherichia coli is a type of bacteria, as a prokaryotic organism is much more smaller than a eukaryotic cell such asa the white blood cell. Escherichia coli is up to 2 micrometers in diameter.
Chickenpox virus are among the largest viruses, they are from 150 to 200 nanometers in diameter.
Ribosomes vary on size depending if they are Prokaryotic or Eukaryotic, where the first are up to 20 nanometers and the second are up to 30 nanometers.
Prion fibrils are aggregates comprised of several protein units. It size varies depending on the number of proteins, but the ones containing around 200 units can reach up to 27 nanometers.
Water molecule is comprised of two atoms of oxygen and one atom of hydrogen, its size is measured with picometers (1 picometer is equal to 1000 nanometers). A water molecule has a size of 275 picometers.
Sulfur atom is the smallest in the list. Its size is around 100 picometers.
Why do melting ice caps make Earth warmer?
The correct answer is C. Albedo decreases.
When the albedo is lower, more radiation from the Sun gets absorbed by the planet resulting in rise of temperature. When the snow covered area warms up and melts, the albedo goes down and more sunlight is absorbed in that area and the temperatures increase.
