2.4: I Need Help - Biology

2.4: I Need Help - Biology

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2.4: I Need Help

2.4: I Need Help - Biology

What is 2,4-D?

2,4-D is an herbicide that kills plants by changing the way certain cells grow. 2,4-D comes in several chemical forms, including salts, esters, and an acid form. The toxicity of 2,4-D depends on its form. The form also affects what will happen to 2,4-D in the environment and what impacts it may have, especially on fish. 2,4-D is used in many products to control weeds, and it is often mixed with other herbicides in these products.

2,4-D was first used in the United States in the 1940s. Agent Orange, an herbicide used during the Vietnam War, contained both 2,4-D and 2,4,5-T. Dioxin, a by-product of 2,4,5-T, led to the ban of Agent Orange.

What are some products that contain 2,4-D?

Products containing 2,4-D may be liquids, dusts, or granules. The liquid forms may be concentrated or ready-to-use. There are over a thousand products with 2,4-D in them that are sold in the United States.

Always follow label instructions and take steps to avoid exposure. If any exposures occur, be sure to follow the First Aid instructions on the product label carefully. For additional treatment advice, contact the Poison Control Center at 1-800-222-1222. If you wish to discuss a pesticide problem, please call 1-800-858-7378.

How does 2,4-D work?

2,4-D kills broadleaf weeds but not most grasses. 2,4-D kills plants by causing the cells in the tissues that carry water and nutrients to divide and grow without stopping. Herbicides that act this way are called auxin-type herbicides.

How might I be exposed to 2,4-D?

Products with 2,4-D may be used on farms, home lawns, roadsides, industrial areas, and pastures. You may be exposed if you are applying 2,4-D and you get it on your skin, breathe it in, or eat or smoke afterwards without washing your hands. You also may be exposed if you touch plants that are still wet with spray. You can limit exposure by following the label carefully if you are using products that contain 2,4-D. You can also stay away from grass or plants that have been treated until the leaves are dry.

What are some signs and symptoms from a brief exposure to 2,4-D?

Pure 2,4-D is low in toxicity if eaten, inhaled, or if it contacts the skin, and some forms are low in toxicity to the eyes. However, the acid and salt forms of 2,4- D can cause severe eye irritation. People who drank products containing 2,4- D vomited, had diarrhea, headaches, and were confused or aggressive. Some people also had kidney failure and skeletal muscle damage. People who spilled 2,4-D on their skin developed skin irritation. Breathing 2,4-D vapors can cause coughing, a burning feeling in the airway, and dizziness.

Pets may be exposed to 2,4-D if they touch grass or other plants still wet from spraying and then groom their feet or fur, if they drink the pesticide, or possibly if they eat grass that has been treated with 2,4-D. Dogs may be more sensitive to 2,4-D than other animals. Dogs and cats that ate or drank products with 2,4-D in them developed vomiting, diarrhea, loss of appetite, lethargy, drooling, staggering, or convulsions. See the fact sheet on Pets and Pesticide Use for more information.

What happens to 2,4-D when it enters the body?

In humans, 2,4-D is not absorbed well through the skin or lungs, but it is absorbed into the body if swallowed. Sunscreen, insect repellents, and drinking alcohol may increase how much 2,4-D is absorbed through the skin. Once inside, 2,4-D moves throughout the body but does not build up in any tissues. The human body gets rid of most of the 2,4-D in the urine without changing it into anything else. More than 75% of the absorbed 2,4-D leaves the body in the first 4 days after exposure.

Is 2,4-D likely to contribute to the development of cancer?

Scientists have not found a clear link between 2,4-D and cancer in people. Because 2,4-D is often mixed with other herbicides, it is difficult to tell if 2,4-D or one of the other herbicides might be linked to cancer. Some studies have suggested that there may be links between non-Hodgkin's lymphoma and exposure to 2,4-D by itself, but other studies have not found any evidence of this.

In 2004, the EPA decided that 2,4-D could not be classified with regard to its ability to cause cancer because there was not enough data.

Has anyone studied non-cancer effects from long-term exposure to 2,4-D?

Animals fed high doses of 2,4-D for several weeks sometimes had fewer young or the young did not have normal skeletons. This only happened if the amount of 2,4-D fed to the mothers was enough to affect the mothers. 2,4-D has not been linked to health problems in human mothers or infants.

Are children more sensitive to 2,4-D than adults?

While children may be especially sensitive to pesticides compared to adults, there are currently no data to conclude that children have increased sensitivity specifically to 2,4-D.

What happens to 2,4-D in the environment?

2,4-D goes through different changes in the environment depending on its form. Most of the time, 2,4-D breaks down in soil so that half of the original amount is gone in 1-14 days. This breakdown time is called the "half-life" of the pesticide. One form of 2,4-D, the butoxyethyl ester, had a much longer half-life in aquatic sediment of 186 days.

2,4-D is broken down by bacteria in water and in soil. Water alone can also break down 2,4-D. 2,4-D has been found at low levels in shallow groundwater and streams in both rural and urban areas.

Can 2,4-D affect birds, fish, or other wildlife?

How 2,4-D affects animals and plants depends on the form of 2,4-D. Some of the ester forms of 2,4-D can be very toxic to fish and other aquatic life. The salt forms may be only slightly toxic to aquatic animals. Aquatic animals are more sensitive to 2,4-D as water temperature rises. 2,4-D may be moderately toxic to practically non-toxic to birds if they eat it. Eggs sprayed with 2,4-D still hatched and the chicks were normal. 2,4-D is practically non-toxic to honeybees. It is not expected to be a hazard to other beneficial insects.

GCSE biology help

hi can someone help me with this q 5.5. plsss

Not what you're looking for? Try&hellip

The genotype is Dd this is because they produce one daughter who doesn&rsquot have the disorder and that wouldn&rsquot be possible if the genotype was DD due to the disorder being a dominant trait.

Punnet square: we know the parent genotype are the same as parent 1 and 2 due to their ability to produce a daughter who is totally unaffected and therefore dd

D d
d Dd dd
d Dd dd
So both children in the left hand column would have the disorder and therefore thats 2/4 or the probability is 50:50.

The diagram shows it&rsquos not on the Y chromosome because 3,11 and 12 are all female yet have the disorder. Females do not have a Y chromosome so therefore the allele cannot physically be carried on the Y chromosome (otherwise it would be impossible for females to have it) and must be carried on a different one.

Hope that&rsquos helpful for you!

(Original post by Wannabevet133)
The genotype is Dd this is because they produce one daughter who doesn&rsquot have the disorder and that wouldn&rsquot be possible if the genotype was DD due to the disorder being a dominant trait.

Punnet square: we know the parent genotype are the same as parent 1 and 2 due to their ability to produce a daughter who is totally unaffected and therefore dd

D d
d Dd dd
d Dd dd
So both children in the left hand column would have the disorder and therefore thats 2/4 or the probability is 50:50.

The diagram shows it&rsquos not on the Y chromosome because 3,11 and 12 are all female yet have the disorder. Females do not have a Y chromosome so therefore the allele cannot physically be carried on the Y chromosome (otherwise it would be impossible for females to have it) and must be carried on a different one.

Hope that&rsquos helpful for you!

hey thank you for helping me out yes i understand it much better now

Structures found only in Plant cells

1) All plant cells have a thick rigid cell wall made of the carbohydrate cellulose. The cell wall allows plant cells to become turgid since when the cell takes in water by osmosis, the rigid cell wall prevents the cell from bursting. The cell wall also acts as a transport pathway across plant tissues and can provide a barrier to some pathogens.

2) All plant cells have a large permanent central sap vacuole. This organelle is bounded by a membrane called the tonoplast and in many plant cells takes up the majority of the volume of the cell.

The sap vacuole provides a compartment in the cell into which excretory molecules can be moved to stop them poisoning the cytoplasm. It also plays a role in the water balance of plant cells since because of all the solute dissolved in it, the cell sap has a low water potential. This helps draw in water by osmosis from the cytoplasm and hence from outside the cell across the cell membrane.

3) Many but not all plant cells contain chloroplasts. These are organelles associated with the process of photosynthesis. Chloroplasts can be recognised in a light microscope image as small, green structures in the cell. The green pigment comes from the chlorophyll molecules that trap energy from sunlight. In an electron micrograph, chloroplasts are distinguished due to their stacks of membrane discs called grana.

Which frequency should you choose?

A 2.4 GHz connection travels farther at lower speeds, while 5 GHz frequencies provide faster speeds at shorter range. Which frequency you choose will depend on where and how you use your WiFi connection most.

A lot of electronic devices and appliances use the 2.4 GHz frequency, including microwaves, baby monitors, and garage door openers. If you have many of these in your home, or if you live in apartments or condos surrounded by other people, that 2.4 GHz band is likely to be congested, which can damage speed and signal quality.

Use 5 GHz for a device closer to the router

If your device doesn’t need to be moved around much and can be located near your router, 5 GHz is your best choice to reduce congestion and take advantage of higher speeds. Similarly, if you're doing a lot of high-bandwidth activities online, such as gaming or videoconferencing, it's best to use this frequency and move as close as possible to the router. (Better yet, plug directly into the modem with an Ethernet cable if possible, as a wired connection is always more stable and faster than wireless.)

Use 2.4 GHz for a device farther from the router

On the other hand, on a device that moves around a lot throughout the day (like your smartphone), especially if you have a large home, the 2.4 GHz frequency is your best bet. This wavelength has a longer range and can penetrate solid objects more easily than the 5 GHz band, making it ideal for devices that are taken from room to room or are more distant from the router.

How can I tell if my Wi-Fi is 2.4 GHz?

Roost Smart Devices can only be connected to the 2.4 GHz band on Wi-Fi routers or access points (AP).

  • All Wi-Fi routers have a 2.4 GHz band.
  • Newer routers are often dual-band router, with 2.4 GHz and 5 GHz bands.
  • If both of your 2.4 GHz and 5 GHz Wi-Fi bands have the same name (SSID) and password, you will not have any problem connecting your Roost Smart Home device regardless of which Wi-Fi network band your smartphone is connected to. You do not need to read further.

Easy check of your smartphone's Wi-Fi connection

To find out whether you need to connect to a different Wi-Fi network to set up your Roost device, go to Settings>Wi-Fi (or Wireless & Networks) on your smartphone.

How many Wi-Fi networks do you see that belong to you?

  • I see ONE network:If you only see one Wi-Fi network name that belongs to you, you can proceed with setting up your Roost device with this Wi-Fi connection. (see IMAGE 1 below).
  • I see TWO or more networks: If you see two or more Wi-Fi network names that belong to you, then one may be a 5 GHz band. Please continue reading the article below Image 1.

IMAGE 1, Example of ONE Wi-Fi network: As seen in the iPhone Wi-Fi settings below, this is an example of only one Wi-Fi network name that belongs to the user, "Myhomenetwork." The others (Dark Knight and Snooze) do not belong to the user, and he cannot connect to them as they are password protected.

I have more than one network name that belongs to me. How do I identify my 2.4 GHz band network?

From your smartphone's Wireless settings page, look at the names of your Wi-Fi networks.

  • A 2.4 GHz network may have "24G," "2.4," or "24" appended to the end of the network name. For example: "Myhomenetwork2.4"
  • A 5 GHz network may have "5G" or "5" appended to the end of the network name, for example "Myhomenetwork5"

IMAGE 2, Example of two Wi-Fi network names: Here is an example where the user has more than one network name that belongs to him. He needs to make sure that he is connected to the 2.4 GHz band to set up his Roost device:

What about Guest networks or other network names?

If your Internet Service Provider (ISP) set up your network, they may have set one of your network bands as "Guest" or a different name. You may need to log in to your Wi-Fi router to see which name is associated with which Wi-Fi band.

How do I log in to my Wi-Fi router?

If you have not changed your default user name and password for your WI-Fi router, here is some information on how to log in to your Wi-Fi router for some common brands

Manufacturer Default IP address /login Default User name Default password
Linksys leave blank admin
Netgear admin password
TP-Link or admin admin

If you have a different brand of router from those listed in the table above, you can search on the internet for specific instructions using the manufacturer’s name and “login router.” For example, if you have an ASUS router, you can search on “login ASUS router.”

Once you log into your router, look for the Wireless settings. Here you can see the name of your Wi-Fi bands and the passwords.

Expression of Genes

For a cell to function properly, necessary proteins must be synthesized at the proper time. All cells control or regulate the synthesis of proteins from information encoded in their DNA. The process of turning on a gene to produce RNA and protein is called gene expression. Whether in a simple unicellular organism or a complex multi-cellular organism, each cell controls when and how its genes are expressed. For this to occur, there must be a mechanism to control when a gene is expressed to make RNA and protein, how much of the protein is made, and when it is time to stop making that protein because it is no longer needed.

The regulation of gene expression conserves energy and space. It would require a significant amount of energy for an organism to express every gene at all times, so it is more energy efficient to turn on the genes only when they are required. In addition, only expressing a subset of genes in each cell saves space because DNA must be unwound from its tightly coiled structure to transcribe and translate the DNA. Cells would have to be enormous if every protein were expressed in every cell all the time.

The control of gene expression is extremely complex. Malfunctions in this process are detrimental to the cell and can lead to the development of many diseases, including cancer.

Gene regulation makes cells different

Gene regulation is how a cell controls which genes, out of the many genes in its genome, are “turned on” (expressed). Thanks to gene regulation, each cell type in your body has a different set of active genes—despite the fact that almost all the cells of your body contain the exact same DNA. These different patterns of gene expression cause your various cell types to have different sets of proteins, making each cell type uniquely specialized to do its job.

For example, one of the jobs of the liver is to remove toxic substances like alcohol from the bloodstream. To do this, liver cells express genes encoding subunits (pieces) of an enzyme called alcohol dehydrogenase. This enzyme breaks alcohol down into a non-toxic molecule. The neurons in a person’s brain don’t remove toxins from the body, so they keep these genes unexpressed, or “turned off.” Similarly, the cells of the liver don’t send signals using neurotransmitters, so they keep neurotransmitter genes turned off (Figure 1).

Figure 1. Different cells have different genes “turned on.”

There are many other genes that are expressed differently between liver cells and neurons (or any two cell types in a multicellular organism like yourself).

How do cells “decide” which genes to turn on?

Now there’s a tricky question! Many factors that can affect which genes a cell expresses. Different cell types express different sets of genes, as we saw above. However, two different cells of the same type may also have different gene expression patterns depending on their environment and internal state.

Broadly speaking, we can say that a cell’s gene expression pattern is determined by information from both inside and outside the cell.

  • Examples of information from inside the cell: the proteins it inherited from its mother cell, whether its DNA is damaged, and how much ATP it has.
  • Examples of information from outside the cell: chemical signals from other cells, mechanical signals from the extracellular matrix, and nutrient levels.

How do these cues help a cell “decide” what genes to express? Cells don’t make decisions in the sense that you or I would. Instead, they have molecular pathways that convert information—such as the binding of a chemical signal to its receptor—into a change in gene expression.

As an example, let’s consider how cells respond to growth factors. A growth factor is a chemical signal from a neighboring cell that instructs a target cell to grow and divide. We could say that the cell “notices” the growth factor and “decides” to divide, but how do these processes actually occur?

Figure 2. Growth factor prompting cell division

  • The cell detects the growth factor through physical binding of the growth factor to a receptor protein on the cell surface.
  • Binding of the growth factor causes the receptor to change shape, triggering a series of chemical events in the cell that activate proteins called transcription factors.
  • The transcription factors bind to certain sequences of DNA in the nucleus and cause transcription of cell division-related genes.
  • The products of these genes are various types of proteins that make the cell divide (drive cell growth and/or push the cell forward in the cell cycle).

This is just one example of how a cell can convert a source of information into a change in gene expression. There are many others, and understanding the logic of gene regulation is an area of ongoing research in biology today.

Growth factor signaling is complex and involves the activation of a variety of targets, including both transcription factors and non-transcription factor proteins.

In Summary: Expression of Genes

  • Gene regulation is the process of controlling which genes in a cell’s DNA are expressed (used to make a functional product such as a protein).
  • Different cells in a multicellular organism may express very different sets of genes, even though they contain the same DNA.
  • The set of genes expressed in a cell determines the set of proteins and functional RNAs it contains, giving it its unique properties.
  • In eukaryotes like humans, gene expression involves many steps, and gene regulation can occur at any of these steps. However, many genes are regulated primarily at the level of transcription.

Alcohol dehydrogenase. (2016, January 6). Retrieved April 26, 2016 from Wikipedia:

Cooper, G. M. (2000). Regulation of transcription in eukaryotes. In The cell: A molecular approach. Sunderland, MA: Sinauer Associates. Retrieved from

Kimball, John W. (2014, April 19). The human and chimpanzee genomes. In Kimball’s biology pages. Retrieved from

OpenStax College, Biology. (2016, March 23). Eukaryotic transcription gene regulation. In _OpenStax CNX. Retrieved from[email protected]:[email protected]/Eukaryotic-Transcription-Gene-.

OpenStax College, Biology. (2016, March 23). Regulation of gene expression. In _OpenStax CNX. Retrieved from[email protected]:[email protected]/Regulation-of-Gene-Expression

Phillips, T. (2008). Regulation of transcription and gene expression in eukaryotes. Nature Education, 1(1), 199. Retrieved from

Purves, W. K., Sadava, D. E., Orians, G. H., and Heller, H.C. (2003). Transcriptional regulation of gene expression. In Life: The science of biology (7th ed., pp. 290-296). Sunderland, MA: Sinauer Associates.

Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., and Jackson, R. B. (2011). Eukaryotic gene expression is regulated at many stages. In Campbell Biology (10th ed., pp. 365-373). San Francisco, CA: Pearson.

Socio-scientific Issues

Socio-scientific issues are controversial social issues which relate to science. They have both biological and social implications and are topics on which people hold different opinions or viewpoints. Social implications may be economic, ethical, cultural, or environmental. Examples of socio-scientific issues include global warming, genetic manipulation and the use of 1080 poison.

This EPIC database is a great site which develops critical thinking, allowing students to explore both sides of an issue and draw their own conclusions. You may need a password from your school or local library to access it.

  • Login using your school password (or ask a librarian on AnyQuestions).
  • Halfway down the page, select View All in the Science, Technology and Ethics topic box.
  • Explore the topic list which includes Animal experimentation, Cloning and Medical Ethics.

This website is a fantastic source of opinions from local experts on topical science-related issues. It is aimed at journalists and media, and is maintained by the Royal Society of New Zealand.

  • You will find the search box half way down the page on the right hand side.
  • Search using keywords like 'cloning' or '1080' and explore articles such as Cloning : beyond Dolly the sheep, and 1080 use - is it justified? Scientists respond.

G. Reading Resources

Love reading but want to get better at it?

These are the sites you can turn to when you need help with reading but don’t want (or have the money) to pay for tutors.

By the way, for the frugal book lover in you, don’t forget to read our list of sites where you can download free books.

68. Reading Rockets

Reading Rockets aims to provide information for young readers and parents.

The multimedia literacy initiative includes PBS programs and reading topics from A to Z.

You can also find research and reports, free reading guides and other reading resources here.

69. The Reading Genie

Dr. Bruce Murray is the Reading Genie – an associate professor of Reading Education.

He bases his reading instructions on science and created this database to ease those learning to read into reading and spelling.

It includes lessons, books, materials, and resources.

Functional biology of intestinal goblet cells

Goblet cells reside throughout the length of the small and large intestine and are responsible for the production and maintenance of the protective mucus blanket by synthesizing and secreting high-molecular-weight glycoproteins known as mucins. To elucidate the role of goblet cells in the biology of the intestinal tract, an overview of the physiological implications of the mucus gel is presented, including a concise review of the products secreted by the cell. Because of the unique nature of this highly polarized exocrine cell, the maturational reorganization of the cytoarchitecture and the cellular mechanisms by which goblet cells secrete their products are discussed. This includes elucidation of the baseline secretory pathway, which is dependent on the cytoskeleton for granule movement, and the accelerated secretory pathway, which is independent of the cytoskeleton but requires an extracellular signal to occur. Finally, the involvement of goblet cell mucins in the pathophysiology of intestinal neoplasia and ulcerative colitis are presented.

Watch the video: Μιτοχόνδρια - Χλωροπλάστες - Βιολογία (July 2022).


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  2. Avital

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  3. Abdul-Salam

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  4. Dishicage

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  5. Taylor

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  6. Thurleigh

    It's a pity that I can't speak now - I'm forced to go away. But I will be released - I will definitely write that I think on this question.

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