Cells as The Basis of Life Complete
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89 Terms
What are the three main uses of energy in cells?
Movement, synthesis of materials, and maintenance of the internal environment.
Movement in cells includes what processes?
Movement of whole cells, organelles, chromosomes during cell division, vesicles, and active transport.
What is synthesis?
The formation of complex substances by combining simpler chemical entities through chemical reactions.
Name the four major organic compounds synthesised by cells.
Carbohydrates, lipids, proteins, and nucleic acids.
Why do cells need a stable internal environment?
To ensure biochemical reactions occur at optimum efficiency.
What factors must cells regulate to maintain homeostasis?
Waste concentration, oxygen levels, carbon dioxide levels, temperature, and pH.
What is ATP?
Adenosine triphosphate; the main energy carrier molecule in cells.
How is energy released from ATP?
ATP is hydrolysed to ADP and inorganic phosphate (Pi), releasing energy.
Why can't cells use glucose directly for most cellular work?
ATP provides immediate, controllable energy for cellular processes.
Define autotroph
An organism capable of producing complex organic molecules from inorganic substances.
Define heterotroph
An organism that obtains organic molecules from other organisms
What is photosynthesis?
The process by which autotrophs use light energy to produce glucose.
What is a photosynthetic autotroph?
An organism that uses sunlight to synthesise organic molecules.
What is a chemoautotroph?
An organism that uses energy from inorganic chemical reactions to synthesise organic molecules.
Why do heterotrophs depend on autotrophs?
Heterotrophs obtain organic molecules and chemical energy originally produced by autotrophs.
What is the primary energy source for most life on Earth?
The Sun
Define metabolism
All anabolic and catabolic reactions occurring within a cell.
Define anabolic reaction.
A reaction that builds larger molecules from smaller molecules and requires energy.
Examples of anabolic reactions
Photosynthesis, DNA replication, protein synthesis, translation.
Define catabolic reaction.
A reaction that breaks down larger molecules into smaller molecules and releases energy.
Examples of catabolic reactions
Aerobic respiration, hydrolysis, oxidation reactions.
Which type of reaction requires ATP?
Anabolic reactions.
Which type of reaction releases energy?
Catabolic reactions.
Overall purpose of photosynthesis.
To convert light energy into chemical energy stored in glucose.
Where does photosynthesis occur?
Chloroplasts.
What are the two stages of photosynthesis?
Light reactions and Calvin cycle (dark reactions).
Where do light reactions occur?
Thylakoid membranes (grana).
Where does the Calvin cycle occur?
Stroma.
What happens during light reactions?
Water is split, oxygen is released, ATP is produced.
What happens during the Calvin cycle?
Carbon dioxide is fixed into glucose.
What is photolysis?
The splitting of water during light reactions.
What gas is released during photosynthesis?
Oxygen
What is the function of chlorophyll?
To absorb light energy.
Why are thylakoid membranes highly folded?
To increase surface area for light absorption and enzyme attachment.
What is a granum?
A stack of thylakoid membranes.
What is the stroma?
The fluid-filled space inside chloroplasts.
What evidence supports the endosymbiotic theory of chloroplasts?
They contain DNA, divide independently, and possess a double membrane.
What is a limiting factor?
A factor that restricts the rate of photosynthesis.
Name five limiting factors of photosynthesis
Light intensity, light wavelength, carbon dioxide concentration, temperature, and water availability.
Why do green plants appear green?
They reflect green light and absorb mainly red and blue wavelengths.
Why do plants grow poorly under green light?
Green light is reflected rather than absorbed.
How does increasing light intensity affect photosynthesis?
It increases the rate until another factor becomes limiting.
What is cellular respiration?
The process of releasing energy from glucose to produce ATP.
Where does aerobic respiration occur?
Cytoplasm and mitochondria.
What are the three stages of aerobic respiration?
Glycolysis, Krebs cycle, and phosphorylation (electron transport chain).
Where does glycolysis occur?
Cytoplasm
What is the product of glycolysis?
Two molecules of pyruvate.
What is the first stage of aerobic respiration?
Glycolysis
Where does the Krebs cycle occur?
Mitochondria
What is produced during the Krebs cycle?
Carbon dioxide and energy carriers.
What is phosphorylation?
The production of ATP by adding phosphate to ADP.
How many ATP are produced during glycolysis?
2 ATP.
How many ATP are produced during the electron transport chain?
Approximately 34 ATP.
What is the role of ATP synthase?
It synthesises ATP using the proton gradient.
What is chemiosmosis?
The movement of hydrogen ions through ATP synthase
Why are mitochondria abundant in muscle cells?
Muscle cells have high energy requirements.
Why is the inner mitochondrial membrane folded?
To increase surface area for electron transport chains and ATP production.
What are the folds of the inner mitochondrial membrane called?
Cristae
Define anaerobic respiration.
The breakdown of glucose without oxygen.
How many ATP molecules are produced during anaerobic respiration?
2 ATP
What is produced during anaerobic respiration in animals?
Lactic acid
What is oxygen debt?
The oxygen required to break down accumulated lactic acid.
Where does anaerobic respiration occur?
Cytoplasm
Why is anaerobic respiration less efficient than aerobic respiration?
It produces much less ATP per glucose molecule.
What is fermentation?
Anaerobic respiration occurring in plants and yeast.
What products are formed during fermentation?
Ethanol and carbon dioxide.
How many ATP molecules are produced during fermentation?
2 ATP.
Raw materials required for photosynthesis.
Carbon dioxide and water.
Raw materials required for aerobic respiration in autotrophs
Glucose and oxygen.
What ions are required for chlorophyll synthesis?
Iron and magnesium ions.
What ions are required for amino acid synthesis in plants?
Nitrate, sulphate, and molybdenum ions.
What is the waste product of photosynthesis?
Oxygen
What are the waste products of aerobic respiration?
Carbon dioxide and water
Inputs required for aerobic respiration in heterotrophs.
Glucose, oxygen, vitamins, and inorganic ions.
Inputs required for protein synthesis.
Amino acids
Inputs required for movement and nerve function
Sodium, potassium, calcium, and chloride ions.
Waste products of aerobic respiration in heterotrophs
Carbon dioxide and water.
Waste product of anaerobic respiration in animals
Lactic acid.
Waste product of protein hydrolysis.
Urea
What ions are lost during perspiration?
Sodium and chloride ions.
Why do metabolic pathways occur in many small steps?
To reduce energy loss, increase control, and produce useful intermediates.
Why does each metabolic step require a specific enzyme?
Enzymes are substrate-specific and regulate each reaction.
Why would a single-step photosynthesis reaction be impossible?
The activation energy required would be too high.
What are intermediate compounds?
Molecules formed during one stage and used in later stages of a metabolic pathway.
What happens to some energy during each metabolic step?
Some energy is lost as heat.
How does chloroplast structure facilitate photosynthesis?
Folded thylakoid membranes increase surface area for chlorophyll and enzymes.
How does mitochondrial structure facilitate respiration?
Folded cristae increase surface area for electron transport chains and ATP synthesis.
Where are photosynthetic enzymes located?
Thylakoid membranes.
Where are electron transport chain enzymes located?
Inner mitochondrial membrane.