# Make the internet a better place to learn

4

## What is the best way to deal with those preaching climate change denial or questions asked about the validity or debate of climate change?

Kate M.
Featured 1 month ago

With patience and maturity.

#### Explanation:

As Socratic has recently launched the environmental science section, we seem to have an influx of questions along the lines of, "Is climate change real," "What proof is there of climate change," "How can we be sure these aren't natural variations," and so forth. Thus, I think it's a good idea to brainstorm how to best tackle these situations.

For starters, many of these questions are essentially duplicates of one another and you can always mark a question as a duplicate.

In extreme cases, you can also mark a question as inappropriate.

That said, I'd like to remind everyone here that the main mission of Socratic is to teach: to make concepts accessible, to make learning easier, to break concepts down into simpler parts so that learning can occur. That said, reading comments/answers/questions in which people are actively spreading false information or posing questions asking how climate change can be true is certainly frustrating. We've all been there. Don't fight fire with fire though, so to speak. Rather than getting angry, respond clearly and don't get personal.

Ask yourself what are the best facts we have that climate change is caused by humans and is happening? Then ask yourself, how can I clearly communicate those facts? I'd advise against listing ten pieces of evidence. I'd also advise against just providing a link to other websites. Instead, pick a few key pieces of evidence and explain them yourself. Use images, videos, graphs, links to other Socratic concepts, and your words to teach. Remember your basics.

Remember, many people just haven't been taught enough about the science behind climate change or they haven't been taught the concepts well. Hopefully you joined Socratic to help others learn, so try and have some patience and explain these concepts in a way that makes climate change science more accessible and less confusing.

In some cases, a person's religious beliefs conflict with climate change, and this is a really hard situation to handle. Be careful and be considerate of other people's beliefs while maintaining the science behind climate change.

4

## Who were the first people known to produce food through agriculture?

Mandira P.
Featured 4 weeks ago

Agriculture started independently, in different locations of the world. At least eleven centres of origin are recognised. People of each centre domesticated only certain species of plants and animals.

#### Explanation:

Ancient people of China, Peru, Mesopotamia, Indus valley and Nile valley became engaged in farming at least 10,000 years ago. Pigs were domesticated in Mesopotamia 13,000 years ago followed by domestication of sheep and cattle in nearby areas. This is why, fertile crescent of near east is regarded as the birthplace of agriculture, and it is here, man first cultivated wheat.

That does not mean that contributions from other centres are of less importance. Maize, papaya and potato were domesticated in the New World; edible mango, orange, tamarind and spices originated in south east Asia; while litchi and onions were first cultivated in China.

2

## What is the difference between ozone depletion and global warming?

Kate M.
Featured 4 weeks ago

Ozone depletion refers to the thinning and loss of ozone whereas global warming refers to the widespread warming temperatures across the globe.

#### Explanation:

Ozone depletion refers to the thinning and loss of ozone whereas global warming refers to the widespread warming of average temperatures across the globe.

The ozone layer allows some energy in and some energy out. The ozone protects us from UV-B rays, which can be very harmful (these are the rays that cause skin cancer). With less ozone, more UV-B rays reach earth's surface, harming humans and other animals as well as plants.

The hole in the ozone layer does not presently allow enough UV-B radiation to reach earth to contribute to global warming. However, both global warming and ozone depletion are anthropogenic in nature (caused by humans). See this article, "Is there a connection between the ozone hole and global warming?" for more information.

You can read more about ozone depletion here.

2

## What are the causes and effects of ozone depletion?

Kate M.
Featured 2 months ago

See below.

#### Explanation:

Ozone depletion is primarily caused by human activities. The main effect of ozone depletion is an increase in UV-B rays reaching the earth's surface.

Causes : chlorofluorocarbon (CFCs), halons, and other compounds deplete the ozone layer. These chemicals are found in cleaning agents, aerosols, insulating foam, and refrigerants. CFCs and halons break down into chlorine and bromine which in turn destroy the ozone layer.

Effects :
Humans: an increase in UV-B rays means a higher risk of skin cancer, eye cataracts, and blindness. Read more here.

Marine life: Phytoplankton and zooplankton are very sensitive to the amount of light in their environment, and increases in UV-B rays would greatly affect them. Because these organisms are the base of the food chain, declines in their numbers would likely have wide-reaching effects for all marine life. Read more here.

Plants: UV-B rays negatively affect plants, including crops humans rely on. An increase in UV-B rays can mean smaller leaf size, decreased plant growth, and lower quality crops for humans. Plants form the basis for most food chains, thus negative effects would likely cascade to those organisms relying on them. Plants are also very important in terms of respiration, photosynthesis, soil stability, and a decline in plant productivity/reduced plant growth would potentially affect soil erosion and productivity and the carbon cycle. Read more here.

1

## How do humans impact the water cycle?

Kate M.
Featured 4 weeks ago

Humans impact the water cycle in numerous ways.

#### Explanation:

Humans affect the water cycle in numerous ways. Some of our actions purposefully affect the water cycle and other human activities have unintentional consequences on the water cycle.

Purposefully changing water cycle :

The image above shows some examples of how we manipulate various sources of water on earth. We pull water out of the ground in order to use it. We change the flow of water using irrigation. We dam lakes and rivers for electricity and to create manmade lakes and ponds. The Colorado River in the US no longer reaches the ocean at times because humans have altered it so much.

Irrigation:

Groundwater usage in India:

Indirect effects :
Climate change is causing numerous changes to the water cycle. Sea levels are rising in some areas and dropping in others, glaciers are retreating and disappearing affecting rivers, droughts are happening more frequently in some regions and floods in other areas, coastlines are changing and some islands are disappearing, the polar ice cap is melting, and so forth.

The use of pesticides, herbicides, and excess nitrogen for farming runs off into rivers and streams and pollutes groundwater. Deforestation, whether for timber or to clear land for agriculture or development, increases runoff. Certain emissions from industry cause acid rain .

Pollution of groundwater:

1

## What is the largest source of water pollution?

G_Ozdilek
Featured 1 month ago

Agriculture (in the USA) is the 1 source of water pollution

#### Explanation:

The most important contamination sources that cause impairment of water quality in rivers and streams are (1) Agriculture (48%), (2) hydrological changes/modifications (20%), (3) habitat modification (14%) and urban run-off/storm severs (13%) (US EPA, 2002).

Similarly, for lakes, agriculture was found as 1 sector in terms of water pollution (41%). The other sources are hydrologic modification (18%), urban run-off/storm severs (18%), and nonpoint sources (14%) (US EPA, 2002).

Reference:

US EPA (2002). National Water Quality Inventory: 2000 Report. Environmental Protection Agency, Office of Water, EPA-841-R-02-001. Washington, D.C., USA.

Just a quick edit:

Agriculture is the #1 source because mainly of the use of fertilizers. When these fertilizers run into water sources, the water becomes nutrient rich, and algae commonly bloom in great numbers. This depletes the oxygen used by fish and other aquatic life in the stream. Another form of this is cattle feces getting into the water, which has the same effect.

1

## What are the main functions of phosphorus in living organisms?

Martin M.
Featured 1 month ago

The element Phosphorus is used in many fundamental parts of living organisms, including DNA, cell membranes, ATP (energy transferring molecules).

#### Explanation:

In living organisms phosphorus is largely observed as a phosphate group, see the picture below.

As can be seen, the phosphate group has a negative charge. This makes this part of a larger molecule hydrophilic (it can form hydrogen bonds and can dissolve in ${H}_{\text{2}} O$, water)

DNA and other information carriers
DNA are large molecules that have a certain sequence, which codes for the make of proteins in the cell. These DNA strands consist out of 4 different bases placed with a certain sequence along a line.

In the picture above a very schematical single DNA strand is showed. The 4 different bases are coloured and connected to the backbone (the black horizontal line) in a certain way. This backbone is build up out of a lot of phosphate groups! This makes DNA negative and hydrophilic on the outside.

Cell membranes
Every cell has a membrane around it. You can see this like a border to enter or leave the cell. This border consists out of many phospholipids. These are showed below.

The hydrophilic head of a phospholipid is made up from the negatively charged phosphate group.

ATP, the energy storage
Certain molecules in the cells are used for the storage of energy. This energy can be used to activate other processes in the cell. An example of an energy storage molecule is ATP (adenosine triphosphate), which consists out of 3 phosphate groups!

Image Source

If you want to learn more about ATP, check out this video!

1

## How does divergent evolution differ from convergent evolution?

Mandira P.
Featured 4 weeks ago

Generally evolution is divergent: I say so because that is how this earth has today become home to immensely diverse kinds of life.

• Divergent evolution simply means appearance of more than one descendant species from an ancestral species population. Mammalian forelimbs, for example, follow an ancestral pentadactyl limb plan but work very differently in different orders.
• Divergent evolution may lead to appearance of homologous organs. Divergence appears due to adaptation of related organisms in different environmental conditions and habit.

• We also find organisms which evolved superficial/plastic similarity in appearance or similar adaptations in habit to other organisms, with which they are not closely related. This is convergent evolution as exhibited by shark and dolphin: they belong to different vertebrate class but both are adapted to aquatic life.
• Convergent evolution leads to appearance of analogous organs where infrastructure of such organs may differ but the functional achievement remains same. This is because of the fact that similarity in appearance and behaviour evolves due to similar environmental pressure.

1

## What role does transpiration play in the water cycle?

G_Ozdilek
Featured 2 weeks ago

Transpiration is the evaporation of water from internal surfaces of living parts of plants (leaves, stems, etc.).

#### Explanation:

In water cycle, plants have critical roles. We know that forest areas guarantee continuation of streamflow due to water regulation in such areas compared to that in open (plant poor) areas.

Transpiration depends on some parameters, such as atmospheric humidity and temperature, area of plant leaves, stems, etc. Opening and closing the stomata is possibly the plant's most important means of regulating water loss via transpiration.

Transpiration accounts for approximately 10% of all evaporating water. Evaporation occurs from streams, lakes, seas, etc. When you think almost 70% of the Earth is covered by seas, you can understand the magnitude of transpiration.

Let me assume that 30% of evaporation occurs from land area. And one-third of this evaporation is called transpiration.

Plants get water via their root system. While they use water (photosynthesis), they also lose this water by transpiration. However, transpiration is a slower (regulated) process compared to that in evaporation from open water bodies. Soil, soil water, plant activity, meteorological parameters, etc. all have roles in transpiration.

Another important feature of plants in water cycle is that they minimize erosion. Rainfall droplets hit the ground with more than 9 meters per second velocity. If it is an open, bare soil, erosion is a big problem. However, rainfall droplets hit plants first and then hit the ground if surface is covered by green plants. Therefore, plant cover minimized erosion rates.

1

## What is the name of the macromolecule in which phosphorus is found?

Martin M.
Featured 2 weeks ago

Phosphorus if found in DNA, cell membranes and ATP.

#### Explanation:

In living organisms phosphorus is largely observed as a phosphate group, see the picture below.

As can be seen, the phosphate group has a negative charge. This makes this part of a larger molecule hydrophilic (it can form hydrogen bonds and can dissolve in ${H}_{\text{2}} O$, water)

DNA and other information carriers
DNA are large molecules that have a certain sequence, which codes for the make of proteins in the cell. These DNA strands consist out of 4 different bases placed with a certain sequence along a line.

In the picture above a very schematical single DNA strand is showed. The 4 different bases are coloured and connected to the backbone (the black horizontal line) in a certain way. This backbone is build up out of a lot of phosphate groups! This makes DNA negative and hydrophilic on the outside.

Cell membranes
Every cell has a membrane around it. You can see this like a border to enter or leave the cell. This border consists out of many phospholipids. These are showed below.

The hydrophilic head of a phospholipid is made up from the negatively charged phosphate group.

ATP, the energy storage
Certain molecules in the cells are used for the storage of energy. This energy can be used to activate other processes in the cell. An example of an energy storage molecule is ATP (adenosine triphosphate), which consists out of 3 phosphate groups!

Image Source

If you want to learn more about ATP, check out this video!