Name: ___________________________________
Biology B Exam
Starch is a large molecule consisting of glucose units joined by glycosidic bonds. Starch is produced by most green plants and is stored in roots, stems, fruits, and seeds. Starch is present in large amounts in plants like potatoes, wheat, corn, rice and cassava. Because of this, starch is the most common polysaccharide in human diets.
Figure 1: Glucose Figure 2: Starch
Which of the following correctly describes the relationship between glucose and starch molecules?
Glucose is a monosaccharide, and starch is a polysaccharide.
Glucose is a polysaccharide, and starch is a monosaccharide.
Both glucose and starch are monosaccharides.
Both glucose and starch are polysaccharides.
Starch is an example of which of the following biomolecules?
Proteins
Nucleic acids
Lipids
Carbohydrate
Researchers wanted to study the role of starch in plants. They designed an experiment to test the levels of starch content (mg/g) in the leaves of certain plants over the course of a day. Plants in our control group were exposed to full light from hours 0-12, representing the full 12-hour period of light most plants receive during the day. From horse 12-24, the control group was kept in the dark, representing the full 12-hour period of night. An experimental group was exposed to an early night from 0-8 hours and darkness from 8-24 hours. All other variables were kept constant. Starch content was measured in each group. The results are shown in the figure below.
3. Which of the following can be reasonably concluded from the experimental results?
Plants produce starch when performing photosynthesis to store energy.
Plants are unable to use starch when exposed to light.
Plants use starch at night to continue the process of photosynthesis without light energy.
Plants are unable to produce starch while performing photosynthesis.
4. Which of the following is true of the starch that plants produce through photosynthesis?
The starch contains high levels of chemical energy immediately used by humans after eating the plants.
The starch is broken down into glucose molecules, which are used for cellular respiration in the plants.
The starch is a necessary molecule for the light-dependent reactions of photosynthesis.
The starch is an important component of cell membranes and is present in all prokaryotic and eukaryotic cells.
5. Which best describes the relationship between heterotrophs and autotrophs?
Autotrophs produce glucose during photosynthesis, and heterotrophs require glucose to produce ATP during cellular respiration.
Autotrophs can fix atmospheric N2 gas into usable forms of nitrogen needed for heterotrophs to produce protein and ATP molecules.
Heterotrophs require starch molecules from autotrophs to build structural molecules like nucleic acids.
Heterotrophs cannot produce glucose on their own, so they must consume plants to obtain the oxygen atoms required during cellular respiration.
6. The dependent variable in the experiment above was
Time after dawn
Starch content
Type of plant used
Time exposed to light.
The graphs below show the energy changes as proteins are broken down by pepsin enzymes.
7. Which of the following best describes the graphs above?
The solid line shows a reaction without an enzyme because the activation energy is lower than in the dotted line.
The solid line shows a reaction with an enzyme because the activation energy is higher than the dotted line.
The dotted line shows a reaction without an enzyme because the activation energy is higher than the solid line.
The dotted line shows a reaction with an enzyme because the activation energy is lower than the solid line.
A student is investigating how characteristics of a plant cell compare to those of an animal cell. To do this, she took cells from a photosynthetic moss and compared them to human skin cells. The student takes a cheek cell from the inside of her mouth and stains it with methylene blue in order to see the membranes of the cell. The same process is completed for the moss cells. She compares the cheek cell to plant tissue of moss using a light microscope. Both figures use the same magnification.
Figure 1: Skin Cells Figure 2: Moss Cells
8. Upon initial observation, the student notices that the cells in Figure 2 have many green circular
organelles that are not present in the skin cells in Figure 1. Which of the following correctly explains
why is this the case?
The circular organelles are ribosomes and make proteins for the cell.
The circular organelles are nuclei that hold and protect the DNA.
The circular organelles are cell membranes that separate different components of the cell.
The circular organelles are chloroplasts that convert light energy into chemical energy.
9. All cells that the student examined in Figure 1 and 2 contained a nucleus. The main role of the
nucleus isp to hold the genetic information responsible for building all the components of a cell.
Which of the following best identifies the name of the polymer inside the nucleus?
Polysaccharide
Protein
Nucleic Acid
Lipid
10. The role of ATP in all biological systems is to
Speed up biochemical reactions.
Serve as the energy currency of the cells
To break chemical bonds between carbon atoms and glucose.
To build proteins in the cells
11. Which of the following is NOT a function of a cell membrane?
Allows for cellular communication
Responsible of the synthesis of ATP
Maintains cellular homeostasis
Regulates the passage of molecules into and out of the cell.
12. Which of the following is a characteristic of lipids?
They are either fats or oils.
They are composed of nitrogenous bases.
They are not soluble in water.
They are polar molecules.
13. Which of the following makes carbohydrates unique from other biological molecules?
Long-term energy storage is provided by carbohydrates.
Carbohydrates are molecules that always form a ring structure.
Carbohydrates contain a 1:2:1 ratio of carbon to hydrogen to oxygen.
The monomers in carbohydrates are held together by peptide bonds.
14. Which of the following are functions of proteins? Choose two
Energy storage
Cell Signaling
Catalyzing Chemical reactions
Encoding genetic information
Answers:
1. Glucose is a monosaccharide, and starch is a polysaccharide.
2. Carbohydrate
3. Plants use starch at night to continue the process of photosynthesis without light energy.
4. The starch is broken down into glucose molecules, which are used for cellular respiration in the plants.
5. Autotrophs produce glucose during photosynthesis, and heterotrophs require glucose to produce ATP during cellular respiration.
6. Starch content
7. The the dotted line shows a reaction with an enzyme because the activation energy is lower than the solid line.
8. The circular organelles are chloroplasts that convert light energy into chemical energy.
9. Nucleic Acid
10. Serve as the energy currency of the cells
11. Responsible of the synthesis of ATP
12. They are not soluble in water.
13. Carbohydrates contain a 1:2:1 ratio of carbon to hydrogen to oxygen.
14. Cell Signaling and Catalyzing Chemical reactions