Life Processes

The governing concept is plant excretion without specialized excretory organs. Plants may remove gases by diffusion through stomata or other surfaces, lose excess water by transpiration, and store wastes in vacuoles, old leaves, bark, or substances such as gums and resins. When leaves or bark are shed, stored wastes are removed from the plant. Therefore option A is correct; plants do not possess animal-like hearts, lungs, or blood platelets.

The governing concept is photosynthesis and conversion of energy. Chlorophyll in green plants absorbs light energy, which powers the formation of glucose from carbon dioxide and water. The energy captured from sunlight is not simply lost; it becomes stored chemical energy in the bonds of glucose and later other food molecules such as starch. Hence option A is correct. The other choices describe conversions unrelated to autotrophic nutrition and biology.

The governing concept is digestion followed by absorption. Heterotrophic organisms obtain ready-made food, but nutrients such as starches, proteins, and fats are often large, complex molecules that cannot cross the intestinal lining efficiently. Enzymes break them into smaller soluble substances—sugars, amino acids, and fatty acids with glycerol—which can be absorbed and used for energy, growth, and repair. Therefore option A is correct; the other choices confuse digestion with plant transport or gas exchange.

The governing concept is saprophytic nutrition. Fungi usually grow on dead and decaying organic matter, but they do not ingest solid food as animals do. They secrete digestive enzymes onto the material; these enzymes break complex substances into soluble, simpler molecules. The fungus then absorbs those dissolved nutrients through its hyphae. Therefore, option A is correct; the other options describe organs or processes that fungi do not possess.

The governing concept is absorption in the digestive system. The large intestine removes a considerable amount of water and some salts from undigested material before faeces are expelled. If water absorption is impaired, the intestinal contents remain unusually watery, which can lead to loose stools and increased loss of body water. Therefore option A is correct. The other options concern unrelated functions of respiration or plants.

The governing concept is the complementary relationship between photosynthesis and cellular respiration. During photosynthesis, green plants use carbon dioxide and water in light to form glucose and release oxygen. During respiration, cells use glucose and oxygen to release usable energy, producing carbon dioxide and water. Thus the products of one process serve as reactants for the other in an ecosystem. Option A states this relationship accurately; the remaining options confuse unrelated substances and functions.

The governing concept is translocation through phloem. Leaves produce sugars, mainly sucrose, by photosynthesis, and the phloem transports these organic nutrients from source tissues to sinks such as roots, fruits and growing regions. If phloem is damaged, the movement of food to roots may be reduced or interrupted, limiting their growth and respiration. Therefore option A is correct. Xylem, not phloem, carries water, and roots neither pump blood nor form alveoli.

The governing concept is xylem transport and cell turgidity. Xylem vessels carry water and dissolved mineral ions upward from roots to stems and leaves. Leaf cells need water to maintain turgor pressure, support photosynthesis and prevent excessive loss of firmness. If xylem is blocked, the water supply falls, cells lose turgidity and leaves may droop or wilt. Hence option A is correct; the other choices refer to animal organs or unrelated substances.

The governing concept is removal of metabolic wastes. Cellular respiration produces carbon dioxide and water as end products. Carbon dioxide is transported to the lungs and removed during exhalation, while excess water may leave through the kidneys, skin or lungs. Excretion therefore helps maintain a stable internal environment by eliminating unwanted products. Option A is correct. The other choices confuse excretion with photosynthesis, digestion or a function limited to teeth.