Questions
20
Q1
Why do organisms take food?
Organisms take food to obtain energy and materials needed for growth, repair, and maintenance of the body.
Q2
What is the role of acid in our stomach?
Hydrochloric acid in the stomach kills bacteria and provides an acidic medium for the enzyme pepsin to digest proteins.
Q3
What is the function of bile juice?
Bile juice emulsifies fats and creates an alkaline medium for the action of pancreatic enzymes.
Q4
Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Diffusion is too slow to transport oxygen to all cells in large multicellular organisms because the distance between the body surface and deepest cells is too large.
Q5
What criteria do we use to decide whether something is alive?
Visible movement such as walking, breathing, or growth is the most common criterion, but molecular movements like metabolic reactions inside cells are the defining feature of life.
Q6
What processes would you consider essential for maintaining life?
Nutrition, respiration, transportation, and excretion are the essential life processes that maintain the body's functions.
Q7
What are the differences between autotrophic nutrition and heterotrophic nutrition?
Autotrophic nutrition is when organisms make their own food using inorganic sources (e.g., plants using sunlight), while heterotrophic nutrition is when organisms depend on other organisms for food.
Q8
Where do plants get each of the raw materials required for photosynthesis?
Plants get CO2 from the atmosphere through stomata, water from the soil through roots, and sunlight is available freely from the sun; chlorophyll is already present in leaves.
Q9
What is the function of digestive enzymes?
Digestive enzymes break down complex food molecules such as carbohydrates, proteins, and fats into simple, absorbable forms.
Q10
How is the small intestine designed to absorb digested food?
The small intestine has villi, finger-like projections that increase the surface area for absorption, and a rich network of blood capillaries to transport absorbed nutrients.
Q11
What are the different ways in which glucose is oxidized to provide energy in various organisms?
Glucose is oxidised in three ways: aerobic respiration (with O2, producing CO2 + H2O + 38 ATP), anaerobic respiration (without O2, producing ethanol + CO2 + 2 ATP in yeast, or lactic acid + 2 ATP in muscle cells).
Q12
How is oxygen and carbon dioxide transported in human beings?
Oxygen is transported by haemoglobin in red blood cells, and CO2 is transported as dissolved gas, as bicarbonate ions, and bound to haemoglobin.
Q13
How are the lungs designed in human beings to maximise the area for exchange of gases?
The lungs contain millions of tiny air sacs called alveoli, which provide a massive surface area with thin walls and a rich capillary network for efficient gas exchange.
Q14
What are the components of the transport system in human beings? What are the functions of these components?
The human transport system consists of the heart (pumping organ), blood vessels (arteries, veins, capillaries), and blood (fluid medium carrying cells, nutrients, gases, and wastes).
Q15
Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Separation ensures efficient oxygen supply to body cells, supporting high metabolic rates and warm-bloodedness in mammals and birds.
Q16
How are water and minerals transported in plants?
Water and minerals are transported from roots to leaves through xylem vessels by transpiration pull, root pressure, and capillary action.
Q17
How is food transported in plants?
Food (sucrose) is transported from leaves to all plant parts through phloem sieve tubes using energy from ATP (translocation).
Q18
Describe the structure and functioning of nephrons.
Nephrons are the filtering units of the kidney. Each nephron has a Bowman's capsule, glomerulus, and a long tubule. They filter blood, reabsorb useful substances, and produce urine.
Q19
What are the methods used by plants to get rid of excretory products?
Plants excrete oxygen through stomata, CO2 through stomata, store waste in leaves and bark that are shed, and secrete gums and resins.
Q20
How is the amount of urine produced regulated?
The amount of urine is regulated by reabsorption of water in the collecting duct, controlled by the antidiuretic hormone (ADH) released by the pituitary gland.