How do enzymes help digestion?

Which compound plays a pivotal role in both the first and last step of the TCA cycle? a. pyruvate b. oxaloacetate c. oxalate d.

vitfil [10]

Answer:

Option b oxaloacetate is the right one.

Explanation:

There are major eight steps in TCA cycle. Oxaloacetate plays a pivotal role in first and eight steps of cycle.

Step 1. In the first step of the citric acid cycle, acetyl CoA joins with a four-carbon molecule, oxaloacetate, releasing the CoA group and forming a six-carbon molecule called citrate.

Step 8. In the last step of the citric acid cycle, oxaloacetate—the starting four-carbon compound-is regenerated by oxidation of malate. Another molecule of NAD+ is reduced to NADH in the process.

8 0

3 years ago

(a) Identify the most likely mode of transport across the membrane for substance L. Explain how information provided helps deter

Viefleur [7K]

Active transport occurs against the electrochemical gradient. It needs energy to move molecules from the lower concentration side to the higher concentration side. The mode of transport is active transport. 

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There are three main different types of transport across the membrane

Simple diffusion ⇒ Does not need energy to occur
Facilitated transport ⇒ Does not need energy to occur
Active transport ⇒ Needs energy to occur

Active transport is the transport of molecules that move against the electrochemical gradient, so it does need energy to happen.

Molecules move from the lower concentration side to the higher concentration side of the membrane.

Carrier proteins are in charge of active transport. The needed energy might proceed from the ATP molecules or the membrane's electric potential.

In the exposed example, a scientist wants to determine how substance L enters a cells in a culture.

The cells maintain a 120 mM intracellular concentration of substance L.

Varying external concentrations of substance L (10 to 100 mM) in culture medium (Table 1).

Table 1. Rate of entry of substance L into mammalian cells in culture

External concentration of substance(mM) Rate of entry of substance L

10 5%

20 25%

30 45%

40 65%

50 80%

60 90%

70 95%

80 100%

90 100%

100 100%

Now, we need to identify the most likely mode of transport across the membrane for substance L, and explain how information provided helps determine the most likely mode of transport.

We know that the intracellular concentration is 120mM.

As we can see, this concentration exceeds all of the culture media concentrations. Yet, the substance keep moving into the cell.

As the concentration inside the cell is always higher than the concentration outside, we can assume that this is not passive transport because the molecule transport is going against its concentration gradient.

Hence, the remaining option is active transport. And as said before, we can see it because the substance keeps crossing the membrane toward the cell interior despite its concentration being higher in the interior of the cell than in the exterior.

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6 0

3 years ago

Plz give all the answers of reproduction in animal class 8 dav

Natasha2012 [34]

I am generally confused as to of what you are asking. Can you post something so i can see what you need? I just am confused.

4 0

4 years ago

Distinguish between innate and acquired immunity

mote1985 [20]

Answer:

Innate immunity you are born with.

Acquired immunity you need to work on over time

Explanation:

Poison ivy for example. Come people are born immune to it, while others have to be around it a lot, (agonizingly so), and they will build up immunity to it's poison.

5 0

3 years ago

Refer to Figure 12-2. Which of the following is the series of amino acids encoded by

svetlana [45]

Answer: D

Explanation:

Okay so look at the diagram. Start from the middle and work your way out.

AUG: I find A in the middle (the first four) and then go to the part of the diagram that has U right under the last letter you had, so A. And do the same for U, and you should get methionine.

Repeat this process for the other two.

6 0

3 years ago