Human Nutrition
What is a balanced diet?
A balanced diet contains the right amount of carbohydrates, fats, proteins, vitamins, mineral ions, water and dietary fibre to meet the daily requirements of the body.
What is the function of the phloem?
Conducts manufactured food substances from the leaves to other parts of the plant
What are arteries?
Blood vessels that carry blood away from the heart
What is a clone?
An organism that is genetically identical to their parent due to asexual reproduction
What is puberty?
The stage of human development in which a person becomes physically mature
What is DCPIP? What is its correlation with Vitamin C?
DCPIP: A blue solution that becomes colourless when Vitamin C is added to it
The larger the number of drops needed to turn DCPIP colourless, the smaller the amount of Vitamin C present.
How is the xylem adapted for its function?
It has an empty lumen to reduce the resistance towards water flow
It is strengthened by deposits of a substance called lignin, which prevents collapse of the vessel
What is the composition of blood?
55% Plasma
45% Blood cells and platelets
What are sepals?
Modified leaves which protect and enclose a flower and its other parts in the bud stage
What is a Graafian follicle?
Developed primary follicles containing an egg surrounded by follicle cells and a fluid-filled space
What is emulsification? What causes it, and what type of breakdown is it?
Emulsification is the process of breaking down fats into tiny fat droplets suspended in liquid, forming an emulsion. It is caused by bile, and it is a physical breakdown.
Transpiration pull: The suction force that pulls water up the xylem vessels
Caused due to the evaporation of water from the leaves, which removes water from the xylem and pulls water up the vessels.
What is a phagocyte and its features/function?
A phagocyte is a white blood cell that has a lobed nucleus and is irregular in shape. It can move about and squeeze through the walls of capillaries. It engulfs and destroys foreign bacteria in a process known as phagocytosis.
What are the parts of the stamen?
Filament: The stalk that holds the anther in a suitable place to disperse pollen
Anther: Two lobes containing two pollen sacs, each containing pollen grains that are released once the anther matures
Pollen grains: Containing the male gamete with half the number of chromosomes as a normal cell
What are the adaptations of sperm?
Numerous sperm produced to increase chances of fertilisation
Acrosome present, which is a vesicle that contains enzymes and break down part of the egg's membranes
Tail so that the sperm can swim
Mitochondria to provide energy for the sperm to swim to the egg
What are the types of teeth and their functions?
Incisors: Flattened, chisel-shaped teeth that hold and cut up pieces of food
Canines: Pointed teeth that cut and tear food
Premolars: Teeth with two cusps that crush and grind food
Molars: Teeth with four or more cusps that chew, crush and grind food
What is the importance of transpiration?
It draws water and mineral ions from the roots to the stem and leaves
It removes latent heat of vaporisation, which cools down the plant and prevents it from being scorched
Water transported to the leaves can be used to keep cells turgid, photosynthesis and to replace water lost by the cells.
How are arteries different from veins in terms of structure?
Small lumen relative to diameter vs large lumen relative to diameter
Semilunar valves absent vs valves present
What are the conditions necessary for the germination of seeds?
Oxygen: Needed for aerobic respiration to release energy used for growth and cell division
Suitable temperature: To provide an optimum temperature for enzymes
Water: A solvent for the transport of digested products from the storage tissue (cotyledons) to the embryonic shoot and roots
What are the functions of the amniotic fluid?
It supports and cushions the fetus before birth
It is a shock absorber
It protects the fetus against physical injury as it cannot be compressed
It allows a certain degree of movement for the fetus, which promotes muscular development
It lubricates the birth canal and reduces friction during birth
How is the small intestine adapted for absorption?
Numerous villi that increase the surface area for absorption
One cell thick epithelium that provides a short diffusion distance for nutrients to pass through
Numerous microvilli to further increase the surface area
Many blood capillaries to transport the absorbed glucose and amino acids away to maintain the diffusion gradient
Lacteal to transport the absorbed fats away
Mitochondria for active transport
What factors affect the rate of transpiration and how?
Wind or air movement: The stronger the wind, the higher the rate of transpiration, as the wind maintains the water vapour concentration gradient between the leaf and the atmosphere
Temperature: An increase in temperature increases the rate of evaporation, increasing transpiration
Light: Stomata open and become wider under light, increasing the rate of transpiration
Humidity: When the air outside the leaf is drier, the concentration gradient of water vapour is steeper, increasing the rate of transpiration
What are the uncontrollable factors of heart disease and their reasons?
Age: The risk of a heart attack increases with age
Gender: Males have a greater risk than females
Genetic factors: Family history can play a role, as a high blood pressure and high blood cholesterol can run in the family
What are the features of insect-pollinated flowers that attract insects?
Large flowers that are brightly coloured to attract insects
Nectar is present
Fragrant/sweet-smelling flowers
Larger pollen grains with rough surfaces so that they can cling to the body of insects
Nectar guide present to guide insects
How is HIV transmitted?
Sexual intercourse
Sharing hypodermic needles with an infected person
Blood transfusion with an infected person
Virus can pass from the infected mother to the fetus during pregnancy