Mastering Biology Test Answers 1

Why are violet-to-blue and red photons the most effective at driving photosynthesis?

A. These are the wavelengths of light absorbed by chlorophyll molecules.
B. These are the wavelengths of light transmitted by chlorophylls.
C. These are the wavelengths of light reflected by chlorophylls.
D. These are the wavelengths of light absorbed by carotenoids.

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These are the wavelengths of light absorbed by chlorophyll molecules.

EXPLANATION: These are the wavelengths of light absorbed by chlorophyll molecules. Engelmann showed that violet-to-blue and red photons are the most productive at stimulating photosynthesis. These are the same wavelengths absorbed by chlorophyll.

What molecule is released when water is split in the light reactions of photosynthesis?

A. chlorophyll
B. carbon dioxide
C. NADPH
D. oxygen

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oxygen

EXPLANATION: When water donates electrons to the reaction center of photosystem II, oxygen is released as a by-product. During photosynthesis, the light energy from the sun is captured and stored in the bonds of Sugars.

At what point in photosynthesis is the electromagnetic energy of light first converted into chemical energy?

A. The conversion first occurs when electrons are transferred from excited pigments to an electron carrier in a photosystem.
B. The conversion first occurs when the photosystem II complex enzymes remove electrons from water, leaving protons and oxygen.
C. The conversion first occurs when the proton-motive force drives the production of ATP
D. The conversion first occurs when protons are transferred from the stroma to the lumen side of the thylakoid membrane.

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The conversion first occurs when electrons are transferred from excited pigments to an electron carrier in a photosystem.

EXPLANATION: In photosynthesis, the conversion of the electromagnetic of light energy to chemical energy first occurs when electrons are transferred from excited pigments to an electron carrier in a photosystem.

Suppose that a pigment had a discrete energy state that corresponded to the energy in green light. Where would you draw this energy state on the diagram shown in Figure 10.9?

A: At the same energy level as energy state two.
B: At a lower energy level than energy state one.
C: At an energy level between energy states one and two.
D: At a higher energy level than energy state two.

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At an energy level between energy states one and two.

EXPLANATION: The energy in a green photon is intermediate between the energies in red and blue photons.

Plant leaves contain openings called _____, which allow the diffusion of carbon dioxide into the leaf tissue.

A. mesophyll
B. CAM
C. calvins
D. stomata

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stomata

EXPLANATION: Stomata (singular: stoma) consist of two guard cells and the pore between them.

Chlorophyll molecules donate electrons to an electron acceptor ____.

A. at night
B. when fluorescence occurs
C. in the antenna complex
D. in the reaction center

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in the reaction center

The enzyme that catalyzes the fixation of carbon dioxide in photosynthesis is _____.

A. ATP synthase
B. carbon dioxidase
C. chlorophyll
D. rubisco

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Rubisco
EXPLANATION: Short for ribulose-1,5-bisphosphate carboxylase/oxygenase, catalyzes the addition of CO2 onto ribulose-1,5-bisphosphate.

The molecules that absorb only certain wavelengths of light energy from the sun to begin the photosynthetic reactions are called _____.

A. pigments
B. chloroplasts
C. oxygen
D. stroma

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Pigments.

EXPLANATION: Pigments absorb certain wavelengths of light and can transfer this captured energy to begin photosynthesis.

What two molecules produced during the light-capturing reactions of photosynthesis are used in the Calvin cycle?

A. glucose and oxygen
B. carbon dioxide and oxygen
C. oxygen and water
D. NADPH and ATP

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NADPH and ATP

EXPLANATION: These two molecules are produced in the light-capturing reactions of photosynthesis and are used to provide energy and reducing power to convert carbon dioxide into sugar.

In the Z-scheme ____ is the initial electron donor and ____ is the final electron acceptor.

A. NADPH; oxygen
B. ATP; carbon dioxide
C. water; oxygen
D. water; NADP+

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water; NADP+

EXPLANATION: Water becomes oxidized, releasing oxygen gas, and NADP+ becomes reduced, producing NADPH.

During the Calvin cycle, carbon dioxide is _____ to drive the formation of sugars.

A. oxidized
B. produced
C. recycled
D. reduced

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reduced.

EXPLANATION: Sugars are reduced compared to carbon dioxide. NADPH provides the reducing power.

Why is it not entirely accurate to adopt the common phrase "light-independent reactions" when referring to the Calvin cycle?

A. Although its reactions are not triggered directly by light, they depend on the products of light-capturing reactions.
B. Calvin cycle enzymes are found in the same cellular location as photosystems I and II.
C. Biologists have discovered that its reactions are triggered directly by light.
D. The Calvin cycle occurs only when stomata are open, which is triggered by light.

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Although its reactions are not triggered directly by light, they depend on the products of light-capturing reactions.

EXPLANATION: The Calvin cycle uses the ATP and NADPH produced by the light-capturing reactions to produce glucose from CO2.

The force driving simple diffusion is ________, while the energy source for active transport is ________.

A: the concentration gradient; ADP
B: the concentration gradient; ATP
C: transmembrane pumps; electron transport
D: phosphorylated protein carriers; ATP

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the concentration gradient; ATP

When we first see chiasmata under a microscope, we know that _____.

chiasmata are what we see under a microscope
A: meiosis II has occurred
B: anaphase II has occurred
C: prophase I is occurring
D: separation of homologs has occurred
E: Asexual reproduction has occurred.

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prophase I is occurring

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?

A: prophase
B: metaphase
C: anaphase
D: interphase

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metaphase

Which of the following statements about deuterostomes is false?

A: All deuterostomes have a coelom.
B: All deuterostomes are triploblastic and have three tissue layers.
C: All deuterostomes exhibit radial symmetry in their bodies.
D: All deuterostomes have a similar pattern of early embryonic development.

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All deuterostomes exhibit radial symmetry in their bodies.

Cells require which of the following to form cilia or flagella?

A: actin
B: laminin
C: tubulin
D: intermediate filaments
E: secretory vesicles

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Tubulin

2. Cells require which of the following to form cilia or flagella?

A: centrosomes
B: laminin
C: actin
D: intermediate filaments
E: secretory vesicles

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centrosomes

DNA and RNA provide evidence of evolution because

A: all organisms have nearly identical DNA and RNA
B: no two organisms have exactly the same DNA
C: each RNA codon specifies just one amino acid
D: in most organisms, the same codons specify the same amino acids

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no two organisms have exactly the same DNA

DNA and RNA provide evidence of evolution because no two organisms have exactly the same DNA.

Which of the following could be a nucleotide of RNA?

A: deoxyribose + phosphate group + thymine
B: deoxyribose + phosphate group + uracil
C: ribose + phosphate group + thymine
D: ribose + phosphate group + uracil

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ribose + phosphate group + uracil

The role of RNA is to move information from the nucleus to the ribosomes for protein synthesis. The DNA located in a eukaryotic cell is nucleus. DNA is made of two chains of nucleotides. hydrogen bonds type of bonds hold the chains together. Uracil RNA base pairs with the adenine in DNA. Uracil base is found only in RNA. ribose + phosphate group + uracil could be a nucleotide of RNA.

Which of the following is a consequence of biological magnification?

A: Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.
B: The amount of biomass in the producer level of an ecosystem decreases if the producer turnover time increases.
C: The biomass of producers in an ecosystem is generally higher than the biomass of primary consumers.
D: Only a small portion of the energy captured by producers is transferred to consumers.
E: Populations of top-level predators are generally smaller than populations of primary consumers.

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Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.

Where do transcription and translation occur in eukaryotic cells?

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Transcription: nucleus
Translation: cytoplasm

Where does translation occur in eukaryotes?

A: In the cytoplasm only
B: Both in the nucleus and in the cytoplasm
C: In the nucleus only
D: In neither the nucleus nor the cytoplasm

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In the cytoplasm only

Transcription occurs in the nucleus then the mRNA is transported out and translation occurs in the cytoplasm.

Which of the following would you expect of a eukaryote lacking telomerase?

A: a reduction in chromosome length in gametes
B: production of Okazaki fragments
C: inability to repair thymine dimers
D: a high probability of somatic cells becoming cancerous
E: high sensitivity to sunlight

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a reduction in chromosome length in gametes