1 markBiological molecules are built through molecules being exchanged with the environment.
Which of the following explains the need for the exchange of matter with the environment?
I - For growth
II - Reproduction
III - Maintain organization
IV - Elimination of excess energy
I and II only
II and III only
All of the above
I, II and III only
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1 markBonds hold together the atoms within water, whereas water molecules are held together via intermolecular forces.
Which of the following correctly states the type of bond between atoms in a water molecule?
Hydrogen bonds
Ionic bonds
Covalent bonds
Polar bonds
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1 markWater molecules require cohesion and adhesion in order to interact with other molecules and be transported through molecules.
Which of the following describes the correct definitions of cohesion and adhesion?
Cohesion is… | Adhesion is… | |
|---|---|---|
A | Forces of attraction between molecules of the same type | Attractive forces between molecules of a different type |
B | Attractive forces between molecules of a different type | Forces of attraction between molecules of the same type |
C | Forces of attraction between atoms of the same type | Attractive forces between atoms of a different type |
D | Attractive forces between atoms of a different type | Forces of attraction between atoms of the same type |
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1 markWater molecules are composed of the atoms hydrogen and oxygen, which are held together by covalent and hydrogen bonds.
Which of the following models best demonstrates the arrangement of hydrogen bonds between water molecules? (Hydrogen bonds are depicted by dashed lines.)
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1 markExploring the molecular pathways and physiological importance of carbon, nitrogen, and phosphorus in different biological systems has highlighted their contributions to life’s fundamental processes. Carbon forms the framework of biological molecules, nitrogen is critical for proteins and nucleic acids, and phosphorus is essential for nucleic acids, membrane structure, and energy metabolism.
Cellular membranes contain phospholipids which provide structure and specific physiological characteristics to support the molecular pathways of the cell.
Which of the following models represents the correct arrangement of phosphorus within a phospholipid?
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1 markNitrogen is a key part of building biomass because of its presence in all amino acids and therefore proteins.
Which of the following best describes nitrogen within a protein?
Each amino acid contains an amine group (-NH₂)
Each amino acid contains a nitrate group (-NO2-)
Each protein molecule contains an amine group (-NH₂)
Each protein molecule contains a nitrate group (-NO2-)
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1 markWater is known as a cohesive molecule due to the presence of hydrogen bonding. Water is also adhesive to other molecules.
Which of the following does not use these properties of water to function?
Mass transport through the xylem of plants and blood vessels in animals.
Surface tension on a body of water meets the air to create a film on the body of water.
Capillary action within xylem vessels.
Evaporation of water from the skin during sweating.
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1 markThe covalent bonds within water molecules are described as polar covalent bonds.
Which of the following best explains why the covalent bonds within water are polar?
Hydrogen is less electronegative than oxygen, generating a partial negative charge near the hydrogen atom.
Hydrogen is more electronegative than oxygen, generating a partial positive charge near the hydrogen atom.
Oxygen is more electronegative than hydrogen, generating a partial negative charge near the oxygen atoms.
Oxygen is less electronegative than hydrogen, generating a partial positive charge near the oxygen atoms.
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1 markThe antibiotic ampicillin is water-soluble and administered via intravenous (IV) fluids. Water's ability to dissolve ampicillin allows for efficient absorption and distribution around the body.
Which of the following best explains how water’s polarity contributes to its ability to dissolve substances?
It forms hydrogen bonds with charged molecules
It forms covalent bonds with solutes.
It neutralizes ionic compounds.
It repels nonpolar substances.
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1 markPrimary focal hyperhidrosis is a neurological condition where the sympathetic nervous system overstimulates sweat glands, leading to excessive sweating. Individuals with this condition experience extreme difficulty in regulating body temperature due to excessive fluid loss.
A researcher investigates the cooling effect of sweat by measuring skin temperature before and after evaporative water loss in hyperhidrosis patients.
Which of the following best explains the data in the graph?
As sweat evaporates, covalent bonds are broken causing the dissipation of larger amounts of energy to the environment.
Water has a high heat of vaporization, absorbing thermal energy as it evaporates.
The polar nature of water causes salts to dissolve in an endothermic reaction removing heat energy from the body.
The high specific heat capacity of water means that large amounts of energy are released as sweat evaporates.
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1 markVascular wilt disease is a fungal disease that infects the xylem, blocking water transport. The fungi invade the xylem and produce sticky gums and toxins that clog the vascular tissue leading to broken columns of water.
Which option best explains why vascular wilt disease has a negative effect on plant growth?
Water movement is slowed, reducing the amount of water reaching the leaves
Water is unable to move through the xylem due to disrupted cohesion-tension forces
Water uptake by the roots decreases, limiting the availability of water for transport
Water evaporates too quickly from leaf surfaces, leading to excessive transpiration
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