What are life processes?
Functions that maintain an organism’s structures and prevent their damage and breakdown.
Why does visible movement alone not establish whether something is alive?
Living organisms may lack visible movement while molecular movement continues.
Which processes are needed to maintain life?
Nutrition, respiration, transport of materials, and excretion.
What materials do autotrophs use to make food?
Simple materials such as carbon dioxide and water.
How do heterotrophs obtain food?
They obtain complex food directly or indirectly from autotrophs.
What does photosynthesis convert carbon dioxide and water into?
Carbohydrates.
What happens to water during photosynthesis?
It is split as light energy is converted to chemical energy.
How does Amoeba surround and take in food?
Temporary finger-like extensions surround the food in a food vacuole.
Where does Amoeba break down food, and how do simpler substances enter the cytoplasm?
Complex substances are broken down in the food vacuole, and simpler substances diffuse into the cytoplasm.
In what order does food pass through the human digestive tract?
Mouth, oesophagus, stomach, small intestine, and large intestine.
Through which opening does human digestive waste leave the body?
The anus.
What does salivary amylase do to starch in the mouth?
It breaks starch into simple sugars.
What do gastric glands release into the human stomach?
Hydrochloric acid, pepsin, and mucus.
Where does glucose first break down into pyruvate during cellular respiration?
In the cytoplasm.
What does pyruvate produce in yeast without oxygen?
Ethanol and carbon dioxide.
What does pyruvate produce in mitochondria when oxygen is available?
Carbon dioxide and water.
Which respiration releases more energy, aerobic or anaerobic?
Aerobic respiration.
What is ATP's role in cells?
It is the energy currency used to drive cellular activities.
Why do aquatic organisms breathe faster than terrestrial organisms?
Water contains less dissolved oxygen than air.
What are alveoli, and where does gas exchange occur?
Balloon-like structures at the ends of lung air passages where gases cross walls surrounded by blood vessels.
What happens to the ribs and diaphragm during inhalation?
The ribs lift and the diaphragm flattens.
What happens to the chest cavity and alveoli during inhalation?
The chest cavity enlarges, air enters the lungs, and the alveoli expand.
How does haemoglobin transport oxygen in the body?
It carries oxygen from the lungs to oxygen-deficient tissues.
Why is most carbon dioxide transported dissolved in blood?
Carbon dioxide is more soluble in water than oxygen.
Which blood component transports dissolved food, carbon dioxide, nitrogenous wastes, and salts?
Plasma.
Which blood cells carry oxygen?
Red blood cells.
Where does deoxygenated blood travel from the body before returning oxygenated to the heart?
To the lungs.
In which direction do arteries carry blood relative to the heart?
Away from the heart.
What prevents blood from flowing backward through veins?
Valves.
What does xylem transport from plant roots?
Water and minerals.
What does phloem transport from plant leaves?
Products of photosynthesis to other plant parts.
What is transpiration in plants?
The loss of water vapour from a plant’s aerial parts.
How does transpiration help move water through xylem?
It creates suction that pulls water upward.
What is translocation in plants?
Movement of soluble photosynthetic products and other substances through phloem from leaves to other plant parts.
What is excretion in organisms?
The removal of harmful metabolic wastes from the body.
Which organs make up the human excretory system?
Two kidneys, two ureters, a urinary bladder, and a urethra.
Where is blood filtered in each nephron?
Into Bowman’s capsule.
What happens to useful substances as nephron filtrate passes along the tubule?
They are selectively reabsorbed.
Where does urine travel after leaving the nephron?
Through the ureter to the bladder.
How can plants remove or store excess water and wastes?
They can transpire, store wastes in vacuoles, shed leaves, store resins and gums in old xylem, or release wastes into soil.
Where do organisms obtain food and other raw materials?
From outside the body.
What do chemical reactions convert raw materials into for growth?
Usable energy and molecules.
In what form do plants store unused carbohydrates?
Starch.
In what form do humans store some energy from food?
Glycogen.
How do plants take up water?
Through their roots.
What do plants use nitrogen to make?
Proteins and other compounds.
How do fungi such as bread mould digest and obtain food?
They digest food outside the body and then absorb it.
How do Paramoecium’s cilia help it take in food?
They move food across its surface to a specific intake spot.
What can build up in muscle cells during sudden activity when oxygen is insufficient?
Lactic acid.
What can lactic acid buildup cause in muscle cells?
Cramps.
How much energy does hydrolysis of ATP's terminal phosphate linkage release?
30.5 kJ/mol.
How does water reach fish gills for oxygen uptake?
Fish take water through the mouth and pass it over the gills.
Where does dissolved oxygen enter the blood in fish?
Across the gills.
Which heart chambers keep oxygenated and deoxygenated blood separate in birds and mammals?
Four chambers.
How many heart chambers do amphibians and many reptiles have?
Three chambers.
What enables exchange between blood and surrounding cells?
Capillaries.
What pushes a water column upward through root xylem?
Root pressure.
What causes water to enter roots after root cells take up soil ions?
A reduced concentration difference.
What drives phloem transport toward tissues at lower pressure?
Sucrose loading increases osmotic pressure, drawing in water.
How much filtrate does a healthy adult initially filter per day?
About 180 L.
How much urine does a healthy adult produce per day after reabsorption?
About one or two litres.
Answer 28 questions on Life Processes.
1. What are life processes in an organism?
2. A plant shows no visible movement, but molecular activity continues in its cells. What does this indicate about whether the plant is alive?
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