High School Biology : Understanding Mitochondria and Chloroplasts

Study concepts, example questions & explanations for High School Biology

varsity tutors app store varsity tutors android store

Example Questions

← Previous 1

Example Question #1 : Understanding Mitochondria And Chloroplasts

Where does the Krebs cycle take place in the mitochondria?

Possible Answers:

Outer mitochondrial membrane

Intermembrane space

Inner mitochondrial membrane

Mitochondrial matrix

Correct answer:

Mitochondrial matrix

Explanation:

The mitochondria are the site for aerobic respiration in the cell. Both the Krebs cycle and electron transport chain are found in the mitochondria, while glycolysis (anaerobic metabolism) takes place in the cytoplasm. The Krebs cycle takes place in the mitochondrial matrix, where pyruvate is used to generate NADH and FADH2. These molecules are then taken to the inner mitochondrial membrane, where the electron transport chain is located. The electron transport chain pushes protons into the intermembrane space, creating the proton gradient that fuels ATP synthesis.

Example Question #2 : Understanding Mitochondria And Chloroplasts

What organelle is associated with photosynthesis in algae?

Possible Answers:

Mitochondria

Guard cells

Plasmids

Chloroplasts

Correct answer:

Chloroplasts

Explanation:

Chloroplasts are an organelle that harbors large amounts of the green pigment chlorophyll. The chloroplast converts the energy of sunlight into chemical energy through a process called photosynthesis. This takes place inside a system of membranous sacs called thylakoids within the chloroplast.

Plants, algae, and cyanobacteria all produce energy via photosynthesis. Plants and algae use chloroplasts, but cyanobacteria are prokaryotes and do not contain membrane-bound organelles. Cyanobacteria use internal thylakoid structures to perform photosynthesis.

Plasmids are circular pieces of DNA found in prokaryotes, and are not linked to photosynthesis. Guard cells are responsible for opening and closing stomata on the surface of plant leaves, and are also not involved in photosynthesis.

Example Question #1 : Understanding Mitochondria And Chloroplasts

A researcher analyzes the effects of a particular disease that affects the eye. He observes that the genes responsible for this disease are located on the mitochondria. What can the researcher conclude about this disease?

Possible Answers:

It is maternally inherited and the disease causing genes are located on a double-stranded RNA

It is paternally inherited and the disease causing genes are located on a double-stranded RNA

It is paternally inherited and the disease causing genes are located on a double-stranded DNA

It is maternally inherited and the disease causing genes are located on a double-stranded DNA

Correct answer:

It is maternally inherited and the disease causing genes are located on a double-stranded DNA

Explanation:

Mitochondria are unique organelles because they contain their own double-stranded DNA. The genes on these DNA molecules are always transmitted to the offspring from the mother. During development, the mitochondrial DNA from the sperm (the gamete from father) is destroyed in the embryo. Since all genes in the mitochondria are only inherited from the mother, we can conclude that this disease is maternally inherited. We also know that the genes must be found on double-stranded DNA. There are very small amounts of double-stranded RNA molecules inside mitochondria, but they don’t code for any known diseases.

Example Question #4 : Understanding Mitochondria And Chloroplasts

Which of the following is true regarding mitochondria?

Possible Answers:

It is believed that mitochondria evolved from a parasitic relationship with eukaryotic cells

The mitochondrial matrix is the space between the inner and the outer membrane of the organelle

Mitochondria have their own ribosomes that are distinct from the normal eukaryotic ribosomes

Glycolysis, the Krebs cycle, and oxidative phosphorylation occur in mitochondria

Correct answer:

Mitochondria have their own ribosomes that are distinct from the normal eukaryotic ribosomes

Explanation:

Mitochondria are the site of Krebs cycle and oxidative phosphorylation; however, they are not the site of glycolysis. Glycolysis occurs in the cytosol. Mitochondria have two membranes: the inner and the outer membrane. The space between these two membranes is termed the intermembrane space. The mitochondrial matrix is inside the inner membrane and is the site of Krebs cycle. Scientists theorize that mitochondria and chloroplasts (from plants) were initially prokaryotic organisms that joined with another cell to form a symbiotic relationship, not a parasitic relationship. This theory is called the endosymbiotic theory and it explains the reasons why mitochondria contain DNA.

Mitochondria do have their own ribosomes, which produce unique mitochondrial proteins. Remember, however, that the mitochondria still utilize the normal proteins produced by the ribosomes in the rough endoplasmic reticulum and cytosol.

Example Question #5 : Understanding Mitochondria And Chloroplasts

The mitochondria are commonly considered the powerhouses of the cell. The energy (ATP) necessary for cell function is created within the mitochondria via the process of oxidative phosphorylation (the electron transport chain). In order for oxidative phosphorylation to be effective, certain proteins must maintain a proton gradient between the two membranes that surround the mitochondria.

Studying the structure of the mitochondria, you will notice that the organelle has two membranes. The outer membrane is smooth, while the inner membrane has numerous inversions and folds. These folds are called cristae. What is the purpose of the cristae?

Possible Answers:

They serve as the location where proteins involved in glycolysis reside

No known function exists for the cristae.

The cristae provide greater surface area for the inner mitochondrial membrane, allowing more electron transport proteins in the organelle and more energy to be produced

The folds are a byproduct of the highly acidic environment caused by the proton gradient. They exist to prevent the proton gradient from damaging the outer mitochondrial membrane.

The cristae serve to funnel protons deeper into the organelle, aiding in oxidative phosphorylation

Correct answer:

The cristae provide greater surface area for the inner mitochondrial membrane, allowing more electron transport proteins in the organelle and more energy to be produced

Explanation:

The cristae increase the surface area available within the cell. In order for oxidative phosphorylation of occur, certain proteins must be embedded in the inner mitochondrial membrane. The fold in the membrane allow for a larger surface area, which in turn allows more of these proteins to be embedded. More proteins to create energy means more energy (ATP) for the cell.

Example Question #16 : Cell Structures And Organelles

Which of the following is not true regarding mitochondria and chloroplasts?

Possible Answers:

Chloroplasts are only found in photosynthetic cells, whereas mitochondria are found in animal and plant cells

Only mitochondria are thought to have arisen via endosymbiosis

The inner membrane of mitochondria forms cristae and the inner membrane of chloroplasts form thylakoids

Chloroplasts contain many pigment molecules that absorb sunlight, while mitochondria do not absorb sunlight

Correct answer:

Only mitochondria are thought to have arisen via endosymbiosis

Explanation:

Mitochondria and chloroplasts are plastids, and are thought to have arisen in eukaryotic cells via endosymbiosis. All the other options are true of mitochondria and chloroplasts.

Example Question #6 : Understanding Mitochondria And Chloroplasts

Which of the following organelles is commonly referred to as the powerhouse of the cell?

Possible Answers:

Mitochondria

Lysosome

Nucleus

Golgi apparatus

Rough endoplasmic reticulum

Correct answer:

Mitochondria

Explanation:

The mitochondria are responsible for synthesis of the majority of the cell's ATP. This is why mitochondria are commonly referred to as the powerhouse of the cell. The rough endoplasmic reticulum and Golgi apparatus are involved in protein synthesis and delivery. The nucleus houses the DNA and is the site of transcription and ribosome assembly (nucleolus). The lysosome contains hydrolytic enzymes that are used for degradation of certain materials.

Example Question #18 : Cell Structures And Organelles

All of the following are true of chloroplasts except __________.

Possible Answers:

they are found in animal cells

The chemical energy that they produce is used to make sugars

they are found in plant cells

They contain tiny pigments called chlorophylls

Correct answer:

they are found in animal cells

Explanation:

Chloroplasts are the organelles found in plant cells that contain chlorophyll pigments which conduct photosynthesis in plants , some bacteria, and some protists.  They form glucose molecules, which can be connected to form polysaccharides of starch.  Animal cells do not have chloroplasts. Rather, animals need to eat their food, they cannot produce their own food from the sun.

Example Question #7 : Understanding Mitochondria And Chloroplasts

Which organelle's main function is the conversion of the potential energy of food molecules into ATP?

Possible Answers:

Ribosomes

Mitochondria

Rough endoplasmic reticulum (ER)

Smooth endoplasmic reticulum (ER)

Correct answer:

Mitochondria

Explanation:

Mitochondria is the organelle involved in ATP production. Specifically, the Krebs cycle and electron transport chain occurs in the mitochondria. Smooth ER synthesizes lipids and detoxifies harmful substances. Rough ER and ribosomes are involved in protein synthesis.

Example Question #8 : Understanding Mitochondria And Chloroplasts

Which of the following organelles contain their “own” DNA?

Possible Answers:

Mitochondria

Nuclei

All of these

Chloroplasts

Correct answer:

All of these

Explanation:

All of the listed organelles contain DNA. Scientists have identified nuclear DNA, mitochondrial DNA and chloroplast DNA that are exclusive to these cellular structures.

← Previous 1
Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: