Life Processes

Step 1: Water leaves leaves as vapour. Step 2: This creates water shortage in leaf cells. Step 3: This shortage pulls water upward through xylem.

Step 1: Roots absorb water from soil. Step 2: Too much salt can make water uptake difficult for roots. Step 3: With less water, the plant may wilt.

Step 1: Sugar made in leaves is loaded into phloem. Step 2: This loading uses energy. Step 3: A pressure difference then moves food to parts that need it.

Step 1: Roots absorb water and minerals, so xylem carries them upward. Step 2: Food is made in leaves, but it may be needed anywhere. Step 3: So phloem can move food upward and downward.

Step 1: Phloem carries food made in leaves to roots. Step 2: Ring removal of bark can break the phloem path. Step 3: Roots will receive less food and their growth will be affected.

Step 1: Filtration separates wastes and small substances from blood. Step 2: The filtrate can also contain useful water, glucose, and salts. Step 3: Reabsorption returns them to blood.

Step 1: On a hot day, water loss through sweat may increase. Step 2: If less water is drunk, the body tries to conserve water. Step 3: Nephrons reabsorb more water, so urine may become concentrated.

Step 1: Protein use can produce ammonia as waste. Step 2: Ammonia is very harmful to the body. Step 3: The liver converts it into urea, which can be removed in urine.

Step 1: Dialysis uses a semipermeable membrane. Step 2: Small waste substances can pass through it. Step 3: Blood cells are large, so they remain in the blood.

Step 1: Urea is a nitrogenous waste. Step 2: Kidneys filter it from blood and remove it. Step 3: If kidneys fail, urea accumulates in blood and becomes harmful.

Step 1: Plants do not have separate excretory organs. Step 2: They can store some wastes in leaves or bark. Step 3: When old leaves fall, these wastes leave the plant.

Step 1: Nutrition provides materials in the form of food. Step 2: Cells break these materials during respiration. Step 3: This releases energy for life activities.

Step 1: Digestion changes large food molecules into small soluble substances. Step 2: Absorption moves these substances into blood. Step 3: Thus both are different but connected processes.

Step 1: Saprophytes depend on dead and decaying matter. Step 2: They release digestive juices outside to simplify complex matter. Step 3: Then they absorb the simple dissolved substances.

Step 1: A parasite takes food from the host. Step 2: This can reduce nutrients available to the host. Step 3: Therefore, parasitic nutrition can often harm the host.

Step 1: Undigested material reaches the large intestine. Step 2: The large intestine absorbs water from it. Step 3: This prevents unnecessary loss of water from the body.

Step 1: Breathing brings oxygen into the lungs. Step 2: Blood carries this oxygen to cells. Step 3: Cells use this oxygen to break food and release energy.

Step 1: Water has less oxygen than air. Step 2: Continuous water flow over gills brings fresh oxygen. Step 3: This makes gas exchange more effective.

Step 1: Alveoli provide large surface area in lungs. Step 2: If surface area decreases, gas exchange decreases. Step 3: Less oxygen weakens cellular respiration and fatigue increases.

Step 1: Photosynthesis produces glucose and releases oxygen. Step 2: Respiration uses glucose and oxygen. Step 3: Therefore, at the material level, both processes are connected.

Step 1: In a multicellular body, all cells are not directly exposed to the environment. Step 2: Internal cells also need nutrients and oxygen. Step 3: A transport system carries these materials over distances.

Step 1: Cellular activities produce wastes. Step 2: These wastes can be toxic in excess. Step 3: Excretion removes them and keeps cells safe.

Step 1: Every cell needs energy to work. Step 2: Growth and repair also need materials. Step 3: Nutrition, respiration, transport, and excretion together maintain this balance.

Step 1: Digestion converts food into simple substances. Step 2: Blood carries these substances to cells. Step 3: Without glucose reaching cells, cellular respiration will produce less energy.

Step 1: Nutrition provides food and respiration releases energy. Step 2: Transport carries materials to the right places. Step 3: Excretion removes wastes, so all processes together maintain life.