BIO 100IN Test 2

What does "n" stand for, haploid or diploid? What does "2n" stand for?

A haploid cell is "n," whereas a diploid cell is "2n."

Explain the difference between a proto-oncogene and a tumor suppressor gene, such as p53.

A proto-oncogene is the segment of DNA that codes for one of the positive cell-cycle regulators. If that gene becomes mutated to a form that is overactive, it is considered an oncogene. A tumor suppressor gene is a segment of DNA that codes for one of the negative cell-cycle regulators. If that gene becomes mutated to a form that is underactive, the cell cycle will run unchecked.

Which of the following accurately describes the end products of glycolysis

ATP, NADH, and pyruvate

After they are broken down into 2-carbon units, where do fatty acids enter the process of aerobic cellular respiration (at what step)? How is this different than glucose catabolism?

After being broken down into smaller pieces, fatty acids enter directly into the citric acid cycle, thus bypassing glycolysis. Glucose, on the other hand, must enter at the beginning step -- glycolysis.

What "powers" ATP synthase so that it can convert ADP to ATP? Is this an active or passive process?

As hydrogen ions pass through ATP synthase (they want to get back to the matrix!) they power ATP synthase so that it can now add a phosphate to ADP to make ATP. Because the hydrogen ions are more concentrated in the intermembrane space, the movement of hydrogen ions through ATP synthase is actually just a passive process!

What type of organism produces cheese, sour cream, and yogurt, and by what process? What gives these foods a sour taste?

Bacteria produce these products through lactic acid fermentation. The sour taste comes from the lactic acid.

Why are carnivores, such as lions, dependent on photosynthesis to survive?

Because lions eat animals that eat plants.

What is the difference between a calorie and a Calorie?

Calorie (with a big "C") contains 1,000 calories (with a little "c"), 1 Calorie equals 1 kilocalorie (kcal), or 1 kilocalorie equals 1,000 calories. Nutritional labels tell us energy content of our food in Calories.

During what phase of interphase does the DNA get duplicated, thus creating duplicated chromosomes?

During the S phase

Where does glycolysis occur? What are its end products?

Glycolysis takes place in the cytoplasm (specifically the cytosol) of the cell, and thus not in the mitochondrion. It produces two pyruvates, a few ATP, and 2 NADH molecules (NAD+ is converted into NADH; the step that drives glycolysis!).

What color of light does chlorophyll reflect?

Green

In what ways are the light reactions different than aerobic cellular respiration?

In the light reactions of photosynthesis water is consumed, whereas in aerobic cellular respiration water is produced. Aerobic cellular respiration consumes oxygen, whereas photosynthesis produces it, and photosynthesis consumes carbon dioxide, whereas aerobic cellular respiration produces it. In terms of energy carriers, plants use NADPH instead of NADH. NADPH phosphorus (P). ATP also serves as an energy carrier in plants.

What happens during carbon fixation?

Inorganic CO2 is converted to an organic compound. Three molecules of CO2 combine with RuBP, and RuBisCO catalyzes a reaction between CO2 and RuBP, which forms a six-carbon compound that is immediately converted into two three-carbon compounds called 3-PGA.

Describe the structure of a duplicated chromosome.

It contains two sister chromatids held together in a region called the centromere.

What is the energy of a photon first used to do in photosynthesis?

It energizes an electron. In photosystem II, a photon of light hits chlorophyll, causing an electron to be energized.

Where in the cell does the citric acid cycle (Kreb's cycle) occur?

It happens in the matrix of the mitochondrion.

What is eutrophication? What causes it and what does it do to the oxygen supply where it occurs?

It involves the excessive growth of algae in aquatic habitats, mainly freshwater ones, such as lakes. Both nitrogen and phosphorus from fertilizers in runoff can lead to this problem. As algae blooms take over, oxygen is depleted from the environment, causing huge die offs of fish and other organisms.

What happens to ATP after phosphorylation of another molecule, such as a muscle contractile protein?

It is converted from ATP (3 phosphates) to ADP (2 phosphates).

What is apoptosis? Do cancer cells do this?

It is programmed cell death, or cell "suicide." If a normal cell is old or worn out, it will undergo apoptosis in order to die and leave an opening for a new cell. Cancer cells avoid this process and thus do not die as they should.

On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

Levels of carbon dioxide (one of the reactants) will fall, and levels of oxygen (a product) will rise. As a result, the rate of photosynthesis will slow down.

What form of cancer it the biggest killer in both men and women? What is the best way to prevent it?

Lung cancer causes the most deaths. The best way to prevent it is to not smoke.

How many cells does meiosis make from the original parent cell (how many cells are there at the end of Telophase II)? How does that compare to mitosis?

Meiosis leads to the formation of 4 total cells, whereas in mitosis there are only two new cells created from the original parent cell.

Besides nonmelanoma skin cancer, what two cancers are the most common in men? In women?

Men: Lung cancer and prostate cancer; women: lung cancer and breast cancer.

In what stage are the chromosomes line up down the middle (equator) of the cell?

Metaphase.

Which molecules are carriers, or "taxi cabs," of electrons and hydrogen ions?

NADH and FADH2. These molecules carry electrons (e-) and hydrogen ions (H+) to the electron transport chain.

During reduction step of the Calvin cycle

NADPH is converted to NADP+

What two nutrients are most limiting to plants?

Nitrogen (N) and phosphorus (P). There is plenty of carbon dioxide in the air!

Which part of the Calvin cycle would be affected if a cell could not produce the enzyme RuBisCO?

None of the cycle could take place, because RuBisCO is essential in fixing carbon dioxide. Specifically, RuBisCO catalyzes the reaction between carbon dioxide and RuBP at the start of the cycle.

What does the conversion of lactic acid to pyruvic acid in the liver require?

Oxygen. This is why you breathe heavy after vigorous exercise.

In what form is most phosphorus in nature?

Phosphate (PO43-)

How do we define a photoautotroph? What are three examples of this type of organism?

Photoautotrophs, including plants, algae, and some bacteria (e.g. cyanobacteria) can us the energy of the sun to make their own food by the process of photosynthesis.

Which of the following statement is true?

Photosynthesis consumes carbon dioxide, whereas aerobic cellular respiration produces it

Which has more energy, a short wavelength or a long wavelength?

Shorter wavelengths have more energy. This is why UV rays and X-rays are dangerous to humans. They are short, high-energy waves.

What occurs during anaphase?

Sister chromatids separate from one another and move toward opposite ends of the cell.

How does utensil size affect our behavior when it comes to how much we eat?

Studies show that the smaller the utensil size the more likely that we will eat less of a food item or drink. Thus, we should choose smaller sizes of plates, cups, etc. if we want to lower our Calorie intake.

How is the hydrogen ion (H+) gradient formed in the mitochondrion?

The jumping of electrons from cytochrome to cytochrome in the inner mitochondrial membrane powers proteins to actively pump hydrogen ions into the intermembrane space, where they become very high in concentration. They are now much more concentrated there than in the mitochondrial matrix where they came from. That makes a gradient that favors the hydrogen ions wanting to go back into the matrix.

From an energetic standpoint, what is more efficient: eating corn or feeding corn to a cow and then eating the cow? Why?

The lower the number of energy transfers (or least number of levels in the food chain or pyramid) the more efficient the system. Thus, eating the corn directly is more efficient than feeding it to the cow, and then eating the cow. Doing so means less net loss of energy..

Plants produce oxygen when they photosynthesize. Where does the oxygen come from?

The splitting of water molecules.

Where in plant cells does the Calvin cycle take place?

The stroma of the chloroplast.

How many chromosomes are in a normal, somatic human cell? What about a sperm?

a somatic cell will have 46 chromosomes, whereas a sex cell, such as a sperm, will have half as many, or 23.

when yeast perform fermentation on sugars in wheat, grapes, they produce ___ as a by product

alcohol

Which of the following is an enzyme found in saliva that begins the breakdown of stratch

amylase

Energy transfers and transformations in living systems are always inefficient because energy is lost in the form of

heat

Where in plant cells does the calvin cycle take place

in the stroma

In the light reactions of photosynthesis, after hydrogen ions pass through ATP synthase they are in the

stroma

The aqueous fluid found inside chloroplasts is known as

stroma

The conversion of FAD to FADH2 and NAD+ to NADH occurs during

the citric acid cycle

ATP contains ___ phosphate groups

three

aerobic cellular respiration

water is produced during the electron transport chain

Fossil fuels include all the following except

wood

What is the structure of ATP and how is it categorized?

ATP, or adenosine triphosphate, is composed of an adenine nucleotide, a ribose sugar, and three phosphates in a row. Thus, chemically it is classified as a nucleic acid.

In what form do plants need nitrogen?

As nitrate (NO3-).

Define the following terms: benign tumor, malignant tumor, and metastasis?

Benign tumors are not cancerous. They don't affect nearby tissues and don't travel to over parts of the body. Malignant tumors, however, are cancerous. Cells can break off from these tumors and travel to other parts of the body in a process called metastasis.

Has rain and snowfall increased or decreased as the result of a warmer climate?

Both have actually increased, on average, when the entire world is taken into account. Some places, however, have become much drier due to climatic shifts.

In what way is a chloroplast structurally similar to a mitochondrion.

Both have inner and outer membranes with a space in between.

How are the light reactions similar to aerobic cellular respiration?

Both occur in a membrane and involve hydrogen ions being actively pumped through protein channels, electrons jumping from protein to protein in an electron transport chain, and ATP synthase making ATP by a passive process.

Compare and contrast alcoholic and lactic acid fermentation.

Both occur in an anaerobic environment, both make ATP and convert NAD+ to NADH in step 1 (glucose to pyruvate), both make carbon dioxide and convert NADH to NAD+ in step 2 (pyruvate to end product), but they differ in their end products. Alcoholic fermentation ends in alcohol (ethanol), whereas lactic acid fermentation ends in lactic acid (lactate).

In order to lose a pound, you need to reduce your weekly caloric intake by about 3,500 Calories. You could lose a pound this week by

Burning off 200 calories through exercise and eating 300 less calories a day

When the cooler fall weather begins to occur, what happens to cause leaves to change their colors?

Cooler temperatures cause the green chlorophyll in leaves to break down. Thus, we can only see the orange, red, and yellow colors as the chlorophyll disappears.

What form of energy is lost during energy transformations and transfers in living systems? How does this relate to entropy?

Energy is lost in the form of heat. That energy loss makes living systems less ordered and more random. Thus, entropy is increased. Heat and entropy are often considered to be one in the same. Without a constant input of energy, living systems cannot remain "ordered" organisms.

What is an example of a catabolic reaction? An anabolic reaction? Which requires a large input of energy and which releases energy?

Examples of catabolic reactions in the body include the breakdown of carbohydrates into short carbon chains, breakdown of triglycerides ("fats") into fatty acids and glycerol, and breakdown of proteins into individual amino acids. These reactions occur during digestion. Examples of anabolic reactions include photosynthesis, where the large molecule glucose is built using smaller molecules and the energy of the sun, and the building of proteins from their smaller amino acid monomers. Anabolic reactions require a large input of energy, whereas catabolic reactions release energy.

How many net ATP are produced by glycolysis?

For each molecule of glucose, glycolysis uses 2 ATP and makes 4 ATP, and thus only 2 net ATP are made.

How many chromosomes are there in each of your daughter cells at the end of meiosis (on your paper at the end of Telophase II)? How many chromosomes would there be in a normal human sex cell (a sperm or an egg) at the end of meiosis?

For this lesson, there were 2 chromosomes in each of the cells (half of the original 4) at the end of meiosis. In normal human sex cells there would be 23 (half of the original 46) at the end of meiosis.

What molecule leaves the Calvin cycle to be converted into glucose?

G3P

Which color(s) of light does chlorophyll reflect?

Green is reflected, and given that plants have a lot of it, that is why plants are green. In the fall, chlorophyll breaks down in leaves, causing them to turn red, orange, and yellow as the other pigments, including the carotenoids, begin to dominate. Eventually, as the leaves start to freeze, the other pigments will be broken down as well, resulting in death for the leaves.

What is a heterotroph? Can heterotrophs do photosynthesis?

Heterotrophs cannot make their own food. They do not have chloroplasts or chlorophyll, so they cannot do photosynthesis. They get their energy by eating other organisms. Humans and other animals are examples of heterotrophs.

What is the difference between competitive inhibition and allosteric inhibition?

In competitive inhibition, another molecule (the inhibitor) competes with the substrate for the active site of the enzyme. Allosteric inhibition, on the other hand, involves the alteration of the shape of the active site, such that the substrate cannot bind to the enzyme's active site for as long as it remains in that conformation.

How many total cells are created from a single parent cell by mitosis?

In mitosis, there are always two new cells created from the original parent cell.

What are the main products of the citric acid cycle? How many times does it occur ("turn") for each molecule of glucose?

It produces many NADH and FADH2 molecules (the real purpose of the cycle), and a lot of carbon dioxide as a waste product. Only a few ATP are made during the citric acid cycle, which "turns" twice for each molecule of glucose. Remember that each molecule of glucose was split into 2 pyruvates, each of which are converted to acetyl CoA and enter the citric acid cycle.

Are most plants C3, C4, or CAM? What about a cactus? Corn?

Most plants are C3. A cactus uses CAM and corn is C4.

Which of the following contains electrons and hydrogen ions?

NADH

Do all animals contain the same number of chromosomes?

No. The number varies from organism to organism.

Describe how oxygen acts as the final electron acceptor. Why does the electron transport chain shut down when oxygen is not present?

Oxygen (O) "grabs" hydrogen ions (H+) that have passed through the ATP synthase, along with electrons from the electron transport chain, to form water (H2O). If oxygen is not there at the end to grab the electrons and hydrogen ions, the electron transport chain backs up, thus shutting it down. Now you see why oxygen is necessary for the production of many ATP by aerobic cellular respiration.

Are somatic cells haploid or diploid? What about sperm and eggs?

Somatic cells are diploid, whereas sperm and eggs are haploid

What organisms can fix nitrogen and where are they found?

Some bacteria in the soil and bacteria living in root nodules of legumes (e.g. beans, peanuts, and pea plants) can do this.

What happens during the M checkpoint?

The cell is checked for proper attachment of microtubules to sister chromatids during metaphase. All sister chromatids must be attached to microtubules in order for mitosis to continue.

In what ways have humans altered the carbon cycle, leading to higher amounts of carbon dioxide in the atmosphere?

The combustion of fossil fuels, including coal, oil, and gas, and burning of plant biomass (e.g. trees) has added large amounts of carbon dioxide to the atmosphere, while at the same time the loss of plants (e.g. through deforestation) has reduced the amount of photosynthesis that removes carbon dioxide from the atmosphere.

Describe the pathway of energy in light-dependent reactions.

The energy is present initially as light. A photon of light hits chlorophyll, causing an electron to be energized. The free electron travels through the electron transport chain, and the energy of the electron is used to pump hydrogen ions into the thylakoid space, transferring the energy into the electrochemical gradient. The energy of the electrochemical gradient is used to power ATP synthase, and the energy is transferred into a bond in the ATP molecule. In addition, energy from another photon can be used to create a high-energy bond in the molecule NADPH.

Name the products and reactants for photosynthesis and aerobic cellular respiration. How do they differ?

The reactants for photosynthesis are carbon dioxide and water, which are also the products of aerobic cellular respiration. The products of photosynthesis are glucose and oxygen, which are also the reactants of aerobic cellular respiration. Thus, in a way the two processes are just the reverse of one another. Energy input from the sun is required to make photosynthesis happen, whereas aerobic cellular respiration release the energy (ATP) in the glucose bonds that had been formed by photosynthesis.

Now, consider the enzymes lactase and amylase. What are their substrates and what does the breakdown of their disaccharide sugars produce?

The substrate, lactose, binds to the active site of the enzyme, lactase. Lactose is broken down into glucose and galactose. The substrate, starch, binds to the active site of the enzyme, amylase. Starch is broken down into many glucose molecules.

Consider the enzyme sucrase. What is the substrate for this enzyme? Where does it bind to the enzyme? What two monosaccharides are released as the final products?

The substrate, sucrose, binds to the active site of the enzyme, sucrase. Sucrose is broken down into glucose and fructose.

What is the ultimate source of energy for photosynthesis? What are the two products of photosynthesis?

The sun provides the energy source for all photoautotrophs. Photosynthesis produces glucose and oxygen.

What structure within the chloroplast contains the pigment chlorophyll? What is a stack of these structures called?

The thylakoid contains the chlorophyll. A stack of thylakoids is called a granum.

How many pairs of homologous chromosomes are in a normal, somatic human cell? How many of those are autosomes?

There would be 23 pairs: 22 autosomes and one pair of sex chromosomes (XX or XY).

In what way can the oceans help to reduce the effects of climate change.

They are a huge reservoir of both carbon dioxide and heat. This allows them to absorb some of the excess carbon and heat, but not enough to prevent climate change from occurring over the long term.

Do chemical bonds represent potential energy or kinetic energy?

They are potential energy. When the bonds are broken during aerobic cellular respiration that energy is released and can now perform work.

In what forms are NADH and FADH2 after they have lost their electrons and hydrogen ions?

They are written as NAD+ and FAD, indicating that they are not carrying electrons or hydrogen ions.

According to NASA, how much has the world warmed, on average, over the last 100 years or so?

They found that it had warmed 0.5 degrees Celsius, or 1 degree Fahrenheit, by the beginning of the 21st century. Some places, such as the poles and southwestern U.S., have warmed by much more.

What do enzymes do for reactions?

They lower the activation energy (the required energy input) so that it is easier for reactions to proceed. Because they help reactions to occur they are called catalysts.

What is the overall purpose of the light reactions in photosynthesis?

To convert solar energy into chemical energy that cells can use to do work. Energy carriers are created to be used in the Calvin cycle, where glucose is actually made.

What is the main purpose of mitosis?

To make more daughter cells that are identical to the original cell. Mitosis makes genetic copies of the parent cell. This occurs during the development of an organism, and when it is necessary to replace dead or dying cells.

What are the most common greenhouse gas emissions that humans are adding to the atmosphere? Which is the most abundant emission and where does it mostly come from?

We are adding carbon dioxide (the most abundant; mainly from fossil fuel use), methane, nitrous oxide, and chlorofluorocarbons to the atmosphere through various activities.

What form of cancer is the second leading cause of cancer-related deaths in women? In men?

Women: breast cancer; men: prostate cancer.

Are the new daughter cells genetically identical to the original parent cell?

Yes, in mitosis the daughter cells are identical to the parent cell.

Do the new daughter cells have the same chromosome number as the original parent cell?

Yes, in mitosis the parent and daughter cells have the same, exact chromosome number!

Are the new daughter cells genetically identical to one another?

Yes, in mitosis they are exactly the same!

Suppose you want to lose a pound of fat this week, and you are able to burn 250 Calories per day through exercise. How many Calories will you also need to reduce from your diet in order to be successful?

You need to "get rid of" 500 Calories per day in order to reach a total loss of 3,500 Calories that week (7 days times 500 Calories per day), which will then allow you to lose one pound of fat. If you burn 250 Calories through exercise, you need to also reduce your caloric consumption by 250 Calories (250 plus 250 equals 500).

Many scientists believe that the increased warming that has been observed over the past 100 years on our plants caused by elevated levels of greenhouse gases in the atmosphere. Which of the following gases is considered to be primarily responsible for this problem?

carbon dioxide

Which of the following greenhouse gases is most abundant in terms of our emissions from activities such as deforestation and fossil fuel use?

carbon dioxide

Excessive growth of algae in lakes an be attributed to excess _____ in fertilizer runoff

phosphorus