BIOL 230 final: exam one test banks

1. Indicate whether the statements below are TRUE or FALSE. If a statement is false, explain why it is false. a. A disaccharide consists of a sugar covalently linked to another molecule such as an amino acid or a nucleotide. b. The hydroxyl groups on monosaccharides are reaction hot spots and can be replaced by other functional groups to produce derivatives of the original sugar. c. The presence of double bonds in the hydrocarbon tail of a fatty acid does not greatly influence its structure.

A. False a disaccharide consists of two sugar molecules that undergo a condensation reaction to form a covalent bond (known as a glycosidic linkage) B. true C. False the presence of a double bond in the hydrocarbon chain of a fatty acid causes a kink in the chain, decreasing its flexibility and packing with neighboring hydrocarbon chains

1. Indicate whether the statements below are TRUE or FALSE. If a statement is false, explain why it is false. A. The chemistry of life is carried out and coordinated primarily by the action of small molecules. B. Carbon-based compounds make up the vast majority of molecules found in cells. C. The chemical reactions in living systems are loosely regulated, allowing for a wide range of products and more rapid evolution.

A. False although small molecules are important in many processes, the chemical reactions in living systems are regulated by the coordinated action of large polymeric molecules B. true C. False the chemical reactions in living systems are very tightly controlled, ensuring that events occur at the proper time and at the proper location inside the cell

1. Indicate whether the statements below are TRUE or FALSE. If a statement is false, explain why it is false. a. Any covalently bonded H atom can participate in a hydrogen bond if it comes in close proximity with an oxygen atom that forms part of a water molecule. b. Protons are constantly moving between water molecules, which means there is an overall equilibrium between hydroxyl ions and hydronium ions in aqueous solutions. c. A strong base is defined as a molecule that can readily remove protons from water. d. Electrons are always shared equally between covalently bonded atoms.

A. false hydrogen atoms that are covalently bonded to carbon atoms do not participate in hydrogen bonds because these hydrogens have almost no net positive charge B. true C. true D.

1. Indicate whether the following statements are TRUE or FALSE. If the statement is false, explain why it is false. A. The terms "prokaryote" and "bacterium" are synonyms. B. Prokaryotes can adopt several different basic shapes, including spherical, rod-shaped, and spiral. C. Some prokaryotes have cell walls surrounding the plasma membrane. D. Oxygen is toxic to certain prokaryotic organisms. E. Mitochondria are thought to have evolved from anaerobic bacteria. F. Photosynthetic bacteria contain chloroplasts.

A.false because archea that are significantly make up class of prokaryotic organisms different from bacteria B. true C.true D. true E. false mitochondria are thought to have evolved from aerobic bacteria F. false photosynthetic bacteria have enzyme systems similar to those found in chloroplasts, which allow them to harvest light energy to fix carbon dioxide

1. Indicate whether the statements below are TRUE or FALSE. If a statement is false, explain why it is false. A. Electron shells fill discrete regions around the nucleus of the atom and limit the number of electrons that can occupy a specific orbit. B. H, C, O, and N are the most common elements in biological molecules because they are the most stable. C. Some atoms are more stable when they lose one or two electrons, even though this means they will have a net positive charge.

A.true B. false CHON are the most common elements in biological molecules because their outer shells are unfilled, making them highly reactive C. true

1. There are 90 naturally occurring elements on the earth, __________ of which compose 96% of the mass of living organisms.

CHON

1. Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. What can be described as the smallest living unit?

a cell

1. Indicate whether the molecules below are inorganic (A) or organic (B). a. glucose b. ethanol c. sodium chloride d. water e. cholesterol f. adenosine g. calcium h. glycine i. oxygen j. iron k. phospholipid

a. organic b. organic c. inorganic d. inorganic e. organic f. organic g. inorganic h. organic i. inorganic j. inorganic k. organic

1. A covalent bond between two atoms is formed as a result of the

a. sharing of electrons

1. Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of species. Which characteristics are useful in an organism chosen for use as a model in laboratory studies?

amenability to genetic manipulation ability to grow under controlled conditions rapid rate of reproduction

1. Proteins are important architectural and catalytic components within the cell, helping to determine its chemistry, its shape, and its ability to respond to changes in the environment. Remarkably, all of the different proteins in a cell are made from the same 20 __________. By linking them in different sequences, the cell can make protein molecules with different conformations and surface chemistries, and therefore different functions.

amino acids

Select the answer that BEST completes the following statement: Chemical reactions in living systems occur in an __________ environment, within a narrow range of temperatures.

aqueous

Select the option that correctly finishes the following statement: A cell's genome

b. contains all of a cell's DNA

Which statement is NOT true about the events/conclusions from studies during the mid-1800s surrounding the discovery of cells?

b. scientists came to the conclusion that new cells can form spontaneously from the remnants of ruptured cells

1. __________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes.

c. hydrophobic

1. Prokaryotic cells do not possess _________.

centrioles membrane bound organelles desmosomes i think nucleus right

The nucleus, an organelle found in eukaryotic cells, confines______ keeping them separated from other components of the cell.

chromosomes

1. Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?

d water

1. An ionic bond between two atoms is formed as a result of the

d. transfer of electrons from one atom to the other

Changes in DNA sequence from one generation to the next may result in offspring that are altered in fitness compared with their parents. The process of change and selection over the course of many generations is the basis of __________.

evolution

1. Which combination of answers best completes the following statement: When atoms are held together by __________ __________, they are typically referred to as __________.

ionic interactions salts

Select the option that BEST finishes the following statement: Evolution is a process

that can be understood based on the principles of mutation and selection

1. Indicate whether the following statements are TRUE or FALSE. If the statement is false, explain why it is false. A. The nucleus of an animal cell is round, small, and difficult to distinguish using light microscopy. B. The presence of the plasma membrane can be inferred by the well-defined boundary of the cell. C. The cytosol is fairly empty, containing a limited number of organelles, which allows room for rapid movement via diffusion. D. The extracellular matrix is the space between individual cells and is exclusively composed of proteins.

A. False the nucleus is one of the largest organelles and is the easiest organelle to discern within a typical cells B. true C. False the cytosol is actually brimming with individual proteins, protein fibers, extended membrane systems, transport vesicles, and small molecules. And although cellular components do move by diffusion, the rate of movement is limited by the space available and the size of the component in question D.

You fertilize egg cells from a healthy plant with pollen (which contains the male germ cells) that has been treated with DNA-damaging agents. You find that some of the offspring have defective chloroplasts, and that this characteristic can be passed on to future generations. This surprises you at first because you happen to know that the male germ cell in the pollen grain contributes no chloroplasts to the fertilized egg cell and thus to the offspring. What can you deduce from these results?

Your results show that not all of the information required for making a chloroplast is encoded in the chloroplast's own DNA; some, at least, must be encoded in the DNA carried in the nucleus. The reasoning is as follows. Genetic information is carried only in DNA, so the defect in the chloroplasts must be due to a mutation in DNA. But all of the chloroplasts in the offspring (and thus all of the chloroplast DNA) must derive from those in the female egg cell, since chloroplasts only arise from other chloroplasts. Hence, all of the chloroplasts contain undamaged DNA from the female parent's chloroplasts. In all the cells of the offspring, however, half of the nuclear DNA will have come from the malegerm cell nucleus, which combined with the female egg nucleus at fertilization. Since this DNA has been treated with DNA- damaging agents, it must be the source of the heritable chloroplast defect. Thus, some of the information required for making a chloroplast is encoded by the nuclear DNA.

1. For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. amino acids micrometer(s) viruses DNA millimeter(s) yeast fatty acids plants meter plasma membranes Cells can be very diverse: superficially, they come in various sizes, ranging from bacterial cells such as Lactobacillus, which is a few __________ in length, to larger cells such as a frog's egg, which has a diameter of about 1 __________. Despite the diversity, cells resemble each other to an astonishing degree in their chemistry. For example, the same 20 __________ are used to make proteins. Similarly, the genetic information of all cells is stored in their __________. Although __________ contain the same types of molecules as cells, their inability to reproduce themselves by their own efforts means that they are not considered living matter.

micrometers millimeters amino acids DNA viruses

Eukaryotic cells are bigger and more elaborate than prokaryotic cells. By definition, all eukaryotic cells have a __________, usually the most prominent organelle. Another organelle found in essentially all eukaryotic cells is the __________, which generates the chemical energy for the cell. In contrast, the __________ is a type of organelle found only in the cells of plants and algae, and performs photosynthesis. If we were to strip away the plasma membrane from a eukaryotic cell and remove all of its membrane-enclosed organelles, we would be left with the __________, which contains many long, fine filaments of protein that are responsible for cell shape and structure, and thereby form the cell's __________.

nucleus mitochondria chloroplast cytosol cytoskeleton

Whereas ionic bonds form a/an __________, covalent bonds between atoms form a/an __________. These covalent bonds have a characteristic bond __________ and become stronger and more rigid when two electrons are shared in a/an __________. Equal sharing of electrons yields a/an __________ covalent bond. If one atom participating in the bond has a stronger affinity for the electron, this produces a partial negative charge on one atom and a partial positive charge on the other. These __________ covalent bonds should not be confused with the weaker __________ bonds that are critical for the three-dimensional structure of biological molecules and for interactions between these molecules

salt molecule length double bond nonpolar polar noncovalent

1. Aromatic carbon compounds such as benzene are planar and very stable. Double-bond character extends around the entire ring, which is why it is often drawn as a hexagon with a circle inside. This characteristic is caused by electron ________________.

resonance