All High School Biology Resources
Example Questions
Example Question #1 : Understanding Mitochondria And Chloroplasts
Where does the Krebs cycle take place in the mitochondria?
Inner mitochondrial membrane
Outer mitochondrial membrane
Mitochondrial matrix
Intermembrane space
Mitochondrial matrix
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?
Guard cells
Mitochondria
Chloroplasts
Plasmids
Chloroplasts
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 #3 : 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?
It is maternally inherited and the disease causing genes are located on a double-stranded DNA
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 RNA
It is maternally inherited and the disease causing genes are located on a double-stranded DNA
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 #1 : Understanding Mitochondria And Chloroplasts
Which of the following is true regarding mitochondria?
The mitochondrial matrix is the space between the inner and the outer membrane of the organelle
It is believed that mitochondria evolved from a parasitic relationship with eukaryotic cells
Glycolysis, the Krebs cycle, and oxidative phosphorylation occur in mitochondria
Mitochondria have their own ribosomes that are distinct from the normal eukaryotic ribosomes
Mitochondria have their own ribosomes that are distinct from the normal eukaryotic ribosomes
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
Which of the following is not true regarding mitochondria and chloroplasts?
Chloroplasts are only found in photosynthetic cells, whereas mitochondria are found in animal and plant cells
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
Only mitochondria are thought to have arisen via endosymbiosis
Only mitochondria are thought to have arisen via endosymbiosis
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?
Mitochondria
Rough endoplasmic reticulum
Golgi apparatus
Nucleus
Lysosome
Mitochondria
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 #7 : Understanding Mitochondria And Chloroplasts
All of the following are true of chloroplasts except __________.
they are found in animal cells
The chemical energy that they produce is used to make sugars
They contain tiny pigments called chlorophylls
they are found in plant cells
they are found in animal cells
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 #5 : Understanding Mitochondria And Chloroplasts
Which organelle's main function is the conversion of the potential energy of food molecules into ATP?
Smooth endoplasmic reticulum (ER)
Rough endoplasmic reticulum (ER)
Ribosomes
Mitochondria
Mitochondria
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 #7 : Understanding Mitochondria And Chloroplasts
Which of the following organelles contain their “own” DNA?
Nuclei
Mitochondria
Chloroplasts
All of these
All of these
All of the listed organelles contain DNA. Scientists have identified nuclear DNA, mitochondrial DNA and chloroplast DNA that are exclusive to these cellular structures.
Example Question #1 : Understanding Mitochondria And Chloroplasts
How is mitochondrial DNA (mDNA) different from nuclear DNA?
mDNA does not have histones
mDNA is inherited solely from the mother
All of these answers
mDNA does not have introns
mDNA is circular rather than linear
All of these answers
Mitochondrial DNA is much smaller and simpler than nuclear DNA, meaning it does not need histones or introns. Mitochondrial DNA is also circular, like bacterial DNA, rather than linear like nuclear DNA. As the ovum is the only contributor of mitochondria to an offspring, all mDNA must therefore be inherited from the mother.