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All living cells respire. This process releases the energy stored in glucose for life processes. Aerobic respiration occurs in the presence of oxygen, whilst anaerobic respiration occurs without it.

Most animals and plants consist of different types of cells organised as tissues, organs and systems. The human respiratory system is a body system adapted for efficient gas exchange.

The major nutrients required for a healthy diet are carbohydrates, proteins and lipids. The digestive system breaks down large molecules of food, which are then absorbed into the bloodstream.

The nervous system enables humans to react to their surroundings and to coordinate their behaviour. The endocrine system secretes hormones into the bloodstream from glands throughout the body.

Plant cells, tissues and organs are adapted to their functions. The stem, root and leaves form an organ system that transports substances into, around and out of a plant. The leaves are the main organ of photosynthesis.

Plants use energy from sunlight to convert carbon dioxide and water into glucose and oxygen during photosynthesis.

Plants can become infected with pathogens such as the tobacco mosaic virus and the rose black spot fungus.

Understanding how to approach exam questions helps to boost exam performance. Question types will include multiple choice, structured, mathematical and practical questions.