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Questions and Answers
Which type of microbe captures energy from light rays?
Cyanobacteria are eukaryotic organisms that contain chloroplasts.
False
What are the two pigments responsible for the blue-green color in cyanobacteria?
Phycoerythrin and phycocyanin
Anoxygenic photosynthetic bacteria do not produce _____ during photosynthesis.
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Match the following types of autotrophs with their characteristics:
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Which group of organisms requires neither sunlight nor organic nutrients?
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Bacteriochlorophyll is capable of absorbing longer wavelengths of light than chlorophyll.
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What is the metabolic pathway where CO2 enters and leaves as glucose?
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Which of the following nutrients is acquired in relatively large quantities and plays a principal role in cell structure and metabolism?
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Heterotrophs can synthesize their own organic carbon from inorganic CO2.
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What must nitrogen be converted to before it can enter a cell?
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The main inorganic source of phosphorus is __________.
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Match the type of nutrient with its description:
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Which of the following is a primary nitrogen source for heterotrophs?
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Oxygen is not involved in the structural functions of the cell.
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What roles does hydrogen play in cellular biochemistry?
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What type of organism is known for producing methane from hydrogen gas and carbon dioxide?
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Aerobic respiration produces glucose as a byproduct.
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What is the role of saprobic microorganisms?
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The movement of water across a selectively permeable membrane is known as ______.
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Match the following transport processes with their descriptions:
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Which type of parasite lives within cells?
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Osmotic pressure is influenced by the concentration of solutes in a solution.
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What is a common adaptation for organisms in hypotonic environments?
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Study Notes
Protein Structure and Stability
- Disulfide bridges are formed by the covalent linking of sulfur atoms of two cysteine amino acids in a protein.
- These bonds help stabilize the protein structure and maintain its shape.
Essential Organic Nutrients
- Growth factors are organic compounds that cannot be synthesized by an organism and must be obtained from the environment.
- Examples of growth factors: amino acids, nitrogenous bases, and vitamins.
Microbial Nutrition
- Microbes obtain nutrients from their environment for cellular activities.
- Essential nutrients are substances required for the growth and survival of an organism.
- Macronutrients are needed in large quantities and are essential for cell structure and metabolism.
- Micronutrients (trace elements) are needed in smaller amounts and are involved in enzyme function and protein structure maintenance.
Inorganic and Organic Nutrients
- Inorganic nutrients are simple molecules containing elements other than carbon and hydrogen.
- Organic nutrients contain carbon and hydrogen and are usually produced by living organisms.
Carbon Sources
- Heterotrophs obtain their carbon from organic sources, relying on other living organisms.
- Autotrophs utilize inorganic CO2 as their carbon source and convert it into organic compounds.
Nitrogen Sources
- Nitrogen is essential for the synthesis of DNA, RNA, and ATP.
- Heterotrophs obtain nitrogen from organic sources and must degrade them into basic building blocks for utilization.
- Before entering the cell, nitrogen must be converted to NH3 (ammonia), the only form directly combined with carbon to synthesize amino acids.
Oxygen Sources
- Oxygen plays structural and enzymatic roles in the cell.
- It is a major component of carbohydrates, lipids, nucleic acids, and proteins.
- Oxygen is also found in inorganic salts.
Hydrogen Sources
- Hydrogen plays multiple roles in cell biochemistry, including:
- Maintaining pH
- Forming hydrogen bonds between molecules
- Serving as the source of free energy in oxidation-reduction reactions of respiration
Phosphorus Sources
- The main inorganic source of phosphorus is PO4 (phosphate), derived from phosphoric acid (H3PO4).
- Phosphate is found in rocks and oceanic mineral deposits.
- It is a key component of nucleic acids, essential for cellular genetics.
Sulfur Sources
- Sulfur is widely distributed in the environment, found in rocks and sediments.
- It is an essential component of vitamins and amino acids methionine and cysteine.
Autotrophs and Their Energy Sources
- Photoautotrophs capture light energy and convert it into chemical energy for cell metabolism.
- They produce organic molecules that can be used by themselves and heterotrophs.
- Chemoautotrophs obtain energy from chemical compounds for cell metabolism.
- Chemoorganic autotrophs use organic compounds for energy and inorganic compounds as their carbon source.
- Lithoautotrophs rely solely on inorganic materials for both energy and carbon, using oxidation and ATP synthesis.
- They fix CO2 through the Calvin cycle, converting it into glucose.
- Methanogens are chemoautotrophs that produce methane from hydrogen gas and carbon dioxide.
- They live in anaerobic environments such as ocean vents and hot springs.
Heterotrophs and Their Energy Sources
- Chemoheterotrophs derive both energy and carbon from organic molecules.
- They obtain this energy through respiration or fermentation and produce ATP.
- Aerobic respiration is the primary energy-yielding pathway in animals, protozoa, fungi, and aerobic bacteria.
- It uses glucose and oxygen as reactants and produces carbon dioxide as a byproduct.
- Aerobic respiration is crucial for Earth's energy balance and metabolic gas regulation.
- Saprobes are free-living microorganisms that feed on dead organic material.
- They play a vital role in the recycling of organic materials.
- Most saprobes have rigid cell walls and release enzymes to digest food into smaller, absorbable particles.
- Parasites derive nutrients from living host cells or tissues.
- They can be categorized as ectoparasites (live on the body), endoparasites (live in organs and tissues), or intracellular parasites (live within cells).
- Obligate parasites cannot survive outside of a living host.
The Movement of Molecules: Diffusion and Transport
- Diffusion is the movement of molecules from an area of higher density or concentration to an area of lower density or concentration.
- Cell membrane permeability and the concentration gradient influence diffusion across the membrane.
The Movement of Water: Osmosis
- Osmosis refers to the movement of water across a selectively permeable membrane.
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Description
This quiz covers essential topics in biochemistry, focusing on protein structure, the formation of disulfide bridges, and the role of organic nutrients in microbial nutrition. It also discusses the distinction between macronutrients and micronutrients crucial for growth and survival. Test your knowledge of how these elements contribute to cellular activities!
