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3 years ago

Which stimulus causes the roots of seedling to grow downard ?

1 answer:

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Gravity
Plant roots always grow downward because specialized cells in root caps detect and respond to gravity. This is an example of a tropism. A tropism is a turning toward or away from a stimulus in the environment. Growing toward gravity is called geotropism.

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A gland is a group of cells or an organ that

olganol [36]

An organ or group of specialized cells in the body that produces and secretes a specific substance, such as a hormone

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3 years ago

Which best describes the limits of science?

vichka [17]

A. Science cannot answer philosophical questions. Philosophical questions could be described as rheoretical questions, such as "what is the purpose of life?" These questions' answers can very from person to person. Science answers questions such as "what is the boiling point of water?", or "what is the chemical structure of water? These are both questions that have the same answer, no matter who is asking them. You just have to have the ability to accurately measure and observe the things involved, or in this case, the temperature of the water when it starts to boil or whe different atoms in the water.

Let's examine the other questions.

B. science can answer only mathematical questions. As you saw in the explanation above, science can also answer other questions, as long as they have a definite answer that we can accurately measure.

C.Science can answer any questions. Again, we have already saw that science cannot answer philosophical questions, so science cannot answer any question.

D. Science can answer any difficult questions. As with the example of the chemical stucture of water, we can answer difficult questions with science. This may seem simple to you, but it would be very difficult if it was not already known!

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2 years ago

Read 2 more answers

Arrange the tiles to show the sequence of the steps in a scientific investigation. make an observation ask questions construct a

puteri [66]

Answer:

The tiles can be arranged as follows:

make an observation
ask questions
construct a hypothesis
test the hypothesis
analyze the results and make conclusions
communicate the result

Explanation

A scientific investigation begins with certain observations. By seeing these observations, a question is made. To answer the question, a hypothesis is generated. A hypothesis is a tentative statement that can either be stated s correct or wrong. To test the hypothesis, experiments are made and results are deduced from the experiments. Based on these results, a hypothesis can be proved as correct or wrong. These results are then communicated to check for their authenticity.

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3 years ago

In this week's experiments, if you replaced glucose with the monosaccharide fructose, predict the results for fructose transport

lbvjy [14]

Answer: Fructose is transported by facilitated diffusion.

Explanation:

Glucose is a monosaccharide with the molecular formula C6H12O6.3 It is a hexose. It is a form of sugar that is found freely in fruits and in honey. Its energy yield is 3.75 Kcal/g under standard conditions.

Fructose is a type of carbohydrate found in vegetables, fruits, and honey. It is a monosaccharide with the same molecular formula as glucose, C6H12O6, but with a different structure, that is, it is an isomer of glucose. Its energetic power is the same as that of glucose, 4 kilocalories per gram, and it is a reducing carbohydrate.

Glucose is the main energy substance of a cell and for its entry it requires a transport protein in the cell membrane, called transporter. The transport of glucose through the cell membrane is carried out by two families of membrane proteins:

Sodium-coupled glucose transporters (SGLT sodium-glucose-transporters), which involves the co-transport of Na+ by the SGLT-1 by maintaining the Na+ gradient thanks to the Na+/K+ pump
Glucose transport facilitation proteins (GLUT)

On the other hand, fructose is absorbed by another type of transporter, called Glut-5, a protein that crosses the membrane 12 times. Finally, the passage of both glucose and fructose into the blood takes place through the Glut-2, a transporter with low affinity and high transport capacity.

If any Glut is considered within the context of a large family of proteins, it can be immediately noticed that they all possess common characteristics that in biochemical terms are called "molecular signature of glucose transporters" and that it is no more than a set of extremely conserved primary amino acidic sequences that determine secondary and tertiary structures (domains or motifs) that are responsible for the functional characteristics of the protein.

Facilitated diffusion is a type of cellular transport where the presence of a carrier or transporter (integral protein, Glut is this example) is necessary for substances to cross the membrane. It happens because the molecules are larger or insoluble in lipids and need to be transported with the help of membrane proteins. So, in the first step, fructose binds to the transport protein, and this changes shape, allowing the passage of this sugar. In this way, fructose concentrations inside the cell are always very low, and the external and internal concentration gradient favours diffusion.

Summarizing, fructose is transported by facilitated diffusion. So if we replaced glucose with fructose we would have seen no change in each conditions. And since fructose is transported by this type of mechanism, there is not a concentration gradient.

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2 years ago

A scientist studied a population of birds for 10 years. During that time, the population was never fewer than 30 birds and never

ahrayia [7]

Answer:

A particular population limiting factor or factors must have been removed

Explanation:

The population of the birds must have been kept between 30 and 50 individuals by population limiting factors such as the presence of predators within the community or competition for resources such as food or spaces.

For the population to shoot up to 90 all of a sudden, it may be that one or more of the population limiting factors has been removed from the population. It could be that a major predator has been removed from the community or the competition for food/space is now significantly reduced due to more food/space in the community.

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2 years ago