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sasho [114]
3 years ago
10

What components of the eukaryotic cell were visible in the onion root tip? Which components were not? Why do you think some comp

onents were more visible than others?
Biology
1 answer:
ruslelena [56]3 years ago
6 0

Looking at the onion root tip under the microscope you can see large, rectangular cells with visible distinct cell walls surrounding it (cells have a more regular shape because of the wall). Inside the cells, you can notice darkly stained nucleus, large vacuoles at the center and sometimes small granules within the cytoplasm. Looking the onion root tip under the microscope is often the way to observe mitosis. Usually, you cannot see organelles such as mitochondria, ribosomes, rough and smooth endoplasmic reticulum, centrioles and Golgi body as they appear translucent and because are too small to be seen under the light microscope (electron microscope required). Also, chloroplasts are not present in an onion cell because it is not a photosynthetic cell.

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Answer:

answer: carbon dioxide

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vovangra [49]

Answer: C. Proteins

Explanation:

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The flow of energy in an ecosystem is best
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The flow of energy in an ecosystem is best described as energy moving in one direction from the sun to the producers then to the consumers. 

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Energy flow is the amount of energy that moves through successive trophic levels of a food chain in an ecosystem. Ecosystem maintain themselves by cycling energy and nutrients.
The energy from sunlight is taken up by producers which use it to produce organic compounds through photosynthesis. The energy is then passed successively to the trophic levels, that is from the producers to the consumers ( primary, secondary, tertiary and quotienary consumers). During this transfer some energy is lost at each trophic level in form of heat. 
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3 years ago
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A poisonous substance enters the food chain through the soul. This substance doesn't break down in the bodies of living organism
Alecsey [184]

Explanation:

Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain.[1] This increase can occur as a result of:

Persistence – where the substance cannot be broken down by environmental processes

Food chain energetics – where the substance's concentration increases progressively as it moves up a food chain

Low or non-existent rate of internal degradation or excretion of the substance – mainly due to water-insolubility

In biomagnification the concentration of the persistent toxins (crosses) increases higher up the food chain.

In this scenario, a pond has been intoxicated. As we go further into the food chain, the toxin concentration increases, causing the top consumer to eventually die of intoxication.

Biomagnification is the build up of toxins in a food chain. The DDT concentration is in parts per million. As the trophic level increases in a food chain, the amount of toxic build up increases. The x's represent the amount of toxic build up accumulating as the trophic level increases. Toxins build up in organism's fat and tissue. Predators accumulate higher toxins than prey.

Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals work their way into lakes, rivers and the ocean, and then move up the food chain in progressively greater concentrations as they are incorporated into the diet of aquatic organisms such as zooplankton, which in turn are eaten perhaps by fish, which then may be eaten by bigger fish, large birds, animals, or humans. The substances become increasingly concentrated in tissues or internal organs as they move up the chain. Bioaccumulants are substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.

Contents

Processes Edit

Although sometimes used interchangeably with "bioaccumulation", an important distinction is drawn between the two, and with bioconcentration.

Bioaccumulation occurs within a trophic level, and is the increase in the concentration of a substance in certain tissues of organisms' bodies due to absorption from food and the environment.

Bioconcentration is defined as occurring when uptake from the water is greater than excretion.[2]

Thus, bioconcentration and bioaccumulation occur within an organism, and biomagnification occurs across trophic (food chain) levels.

Biodilution is also a process that occurs to all trophic levels in an aquatic environment; it is the opposite of biomagnification, thus when a pollutant gets smaller in concentration as it progresses up a food web.

Lipid, (lipophilic) or fat soluble substances cannot be diluted, broken down, or excreted in urine, a water-based medium, and so accumulate in fatty tissues of an organism, if the organism lacks enzymes to degrade them. When eaten by another organism, fats are absorbed in the gut, carrying the substance, which then accumulates in the fats of the predator. Since at each level of the food chain there is a lot of energy loss, a predator must consume many prey, including all of their lipophilic substances.

For example, though mercury is only present in small amounts in seawater, it is absorbed by algae (generally as methylmercury). Methyl-mercury is the most harmful variation of mercury. It is efficiently absorbed, but only very slowly excreted by organisms.[3] Bioaccumulation and bioconcentration result in buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish, etc. Anything which eats these fish also consumes the higher level of mercury the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. For example, herring contains mercury at approximately 0.01 parts per million (ppm) and shark contains mercury at greater than 1 ppm.[4]

DDT is thought to biomagnify and biomagnification is one of the most significant reasons it was deemed harmful to the environment by the EPA and other organizations. DDT is stored in the fat of animals and takes many years to break down, and as the fat is consumed by predators, the amounts of DDT biomagnify. DDT is now a banned substance in many parts of the world.[5]

7 0
3 years ago
When glucose is present, enzyme IIAglc is __________ and LacY is __________. a. phosphorylated; inhibited b. not phosphorylated;
olga_2 [115]

Answer:

Option B, not phosphorylated; inhibited

Explanation:

Glucose 6 acts as a catobolite repressant . A catobolite repressant which is usually a carbon compound inhibits the operon transcription. In the presence of glucose -6, unphosphorylated enzyme IIAGlc  inhibits the transportation system and hence prevents the utilization of lactose. Glucose‐6‐phosphate and other non‐PTS carbon causes inducer exclusion thereby leading to dephosphorylation of enzyme IIAGl without getting transported.

Hence, option B is correct

5 0
3 years ago
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