3. Explain how organisms use chemical energy to drive basic life functions.

I need some help on two homework questions in Biology:

nikitadnepr [17]

1. DNA

2. Transcription

3 0

3 years ago

Write a 600 word report discussing nuclear reactors. The report should include a description of the way a reactor works and the

barxatty [35]

Answer:

Explanation:

A nuclear reactor is an installation capable of initiating, maintaining and controlling the chain fission reactions that take place in the reactor core, consisting of the fuel, coolant, control elements, structural materials and moderator in the case of nuclear thermal reactors.

The core is the part of the reactor where the nuclear chain reaction is produced and maintained.

Components of the core:

The fuel of a nuclear reactor is fissionable material.

Control rod beams provide a rapid means of controlling the nuclear reaction, allowing rapid changes in reactor power and eventual shutdown in case of emergency.

The neutrons produced in fission have a high energy in the form of velocity. Their speed should be reduced to increase the probability of other atoms fissioning and not to stop the chain reaction. This is achieved by elastic collisions of the neutrons with the nuclei of the moderator.

Most of the energy released by fission is in the form of heat. To be able to use this, a refrigerant must pass through the interior of the reactor that absorbs and transports this heat.

In a nuclear chain reaction, a certain number of neutrons tend to escape from the region where it is produced. This neutron leakage can be minimized by the existence of a reflecting medium, thus increasing the efficiency of the reactor.

When the reactor is in operation, a large amount of radiation is generated. Protection is needed to isolate the installation workers from radiation caused by fission products. Therefore, a biological shield is placed around the reactor to intercept these emissions.

A breeder reactor is a nuclear reactor that generates more fissile material in the fuel than it consumes. Considered highly attractive because of their superior fuel economy: a normal reactor consumes less than 1% of the natural uranium that starts the fuel cycle, while a 'breeder' can burn it almost completely. It also generates less waste for the same amounts of energy. Breeders can be designed to use thorium, which is more abundant than uranium. Currently, there is renewed interest in both breeder designs due to the increased price of natural uranium.

All commercial reactors breed fuel, but they have low (though still significant) breeding ratios when compared to machines that are traditionally considered breeders. In recent years, the commercial energy industry has been emphasizing high burn fuels, which last longer in the core of the reactor.

Reproduction of fissile fuel is a common feature in reactors, but commercial reactors are not optimized for this feature which is referred to as improved burning. Up to one-third of all electricity produced in the current U.S. reactor inventory comes from reproducible fuel, and the industry is working hard to increase that percentage over time.

The advantages are:

Generates a large amount of electricity

No production of greenhouse gases

Dependence on oil is reduced

Less damage to the environment

A major disadvantage is the difficult management of the nuclear waste generated.

Nuclear power plants have a limited lifetime. The investment for the construction of a nuclear plant is very high.

4 0

3 years ago

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forsale [732]

Answer:

13 - D

14 - D

15 - C

Explanation:

for 13

A molecule is two or more atoms chemically combined

An example would be carbon dioxide which contains the two atoms, carbon and oxygen

Reasons its not the other answers:

Electrons, Protons and Neutrons are all parts of an atom therefore they cannot be classified as molecules.

For 14

Remember an atom is the most basic unit out of the units we are talking about

The answer would be D

Reasons its not the other answers

Water is considered to be a molecules as it contains two or more atoms (hydrogen and oxygen)

Air is considered to be a mixture as it contains oxygen and nitrogen which can be separated

Salt is considered to be a compound because salt is made up of two atoms (chloride and sodium) in which they are held up by an ionic bond

For 15

The answer would be C (III only)

Carbon hydrogen and oxygen all happen to by atoms

Reasons its not other answer choices:

Like stated previously water is considered to be a molecule therefore we can eliminate the other answer choices

Other notes:

Compounds and molecules both are combinations of two or more atoms however they are not to be mixed together

the main difference between compounds and molecules is how they are held together

Compounds are held together by ionic bonds while molecules are help up by covalent bonds

compounds and molecules are made up of atoms that cannot be separated

Mixtures - A mix of two or more substances that can be separated

3 0

3 years ago

People are biological creatures as well as rational human beings. In order to gain a complete understanding of any aspect of hum

Bogdan [553]

Answer:

The correct answer is option b, that is, four-field approach.

Explanation:

Anthropology refers to the study of human beliefs, behavior, and adaptations. In order to completely comprehend any aspect of human behavior, the field of anthropology adopts a four-field approach. The four sub-disciplines of anthropology are archaeology, cultural anthropology, biological anthropology, and linguistic anthropology.

In archaeology, materials are used generally from past cultures, in order to understand and illustrate human behavior and adaptive strategies via time. Biological anthropology refers to the study of humans as biological species, the research areas comprise diversity in modern human populations, human evolution, and medical anthropology.

The cultural anthropology explores patterns of behavior and belief in historical and contemporary cultures all over the globe. The linguistic anthropology studies and documents languages in terms of acquisition, structure, and use in the transmission of culture. As can be seen that each of the sub-disciplines focuses on distinct characteristics of human adaptation, however, when taken together in a four-field approach it offers a powerful tool for gaining a complete understanding of any aspect of human behavior.

5 0

3 years ago

How do scientists decide when to change or modify their understanding of a particular topic?

Natali5045456 [20]

Answer:

they carry out experiments to understand it

Explanation:

Scientists raise hypotheses which are tested by experiments made under controlled conditions in order to explain a particular topic. When a hypothesis is confirmed by the experimental data, the evidence obtained from this experiment provides the basis to increase the scientific knowledge about a particular issue. In consequence, experimentation can be considered as a critical step in the scientific method and research aims to advance knowledge of a particular phenomenon by confirming a hypothesis, which must be testable (i.e. verifiable as a result of further experimentations).

6 0

3 years ago