Chapter 5: Tissues, Organs and Organ SystemsShort Questions with Answers

Cell → tissue → organ → organ system (the full list: atom, molecule, organelle, cell, tissue, organ, organ system, organism).

Three layers of smooth muscle (outer longitudinal, middle circular, inner oblique) contract and relax to churn the food and mix it with gastric juice, helping its breakdown, and push it on to the intestine.

Its tightly packed, elongated cells lie just beneath the upper epidermis and are rich in chloroplasts; it is the main site of photosynthesis, catching the most light.

The shoot system (stems, branches, leaves, flowers and fruits) supports the plant, carries out photosynthesis and reproduction, and transports materials between roots and leaves.

The ability of an organism to maintain a stable internal environment despite changes in the external environment. It is important because cells work properly only when temperature, pH and the levels of salts, glucose and oxygen stay in the normal range.

The temperature regulating centre in the brain controls it around 37 °C. If temperature rises, it signals sweat glands; sweat evaporates and removes heat. If temperature falls, it signals muscles to shiver, generating heat.

"The whole is greater than the sum of its parts." This describes emergent properties.

A group of similar cells working together to perform specific functions. Animals: epithelial, muscle tissue; plants: epidermal, vascular (xylem, phloem) tissue.

Organ: related tissues working together (heart, lungs, leaf, root). Organ system: multiple organs working together for related functions (circulatory, digestive; root and shoot systems).

Atoms combine to form molecules, which can have different properties from their atoms: water, protein, nucleic acid.

A living entity that can function independently on behalf of the proper functioning of its organ systems, e.g. humans and trees.

New functions created by the interaction of components, present at a higher level but not possible from the individual parts.

Muscle cells together form muscle tissue that can contract and generate force; the tissues of the heart together pump blood.

Roots anchor the plant, absorb water and minerals and store food. Stems support leaves, flowers and fruits and carry water, minerals and food in xylem and phloem.

The loss of water vapour from leaves through small pores called stomata.

Epidermal tissue, mesophyll tissue (palisade and spongy) and vascular tissue (xylem and phloem).

The waxy cuticle reduces water loss and protects; stomata (between guard cells) control gas exchange and loss of water vapour.

Because it consists of two tissues: xylem and phloem.

Plants are non-moving organisms; they need only the root and shoot systems.

Liver: filters blood, produces bile, stores glucose. Kidneys: filter wastes from blood and produce urine.

Epithelial tissue, connective tissue, muscle tissue (three layers) and outer connective tissue.

It activates pepsinogen into the enzyme pepsin, which digests proteins.

Bones, cartilages and tendons; structure, support, protection, framework for muscles, mineral storage and blood cell production.

Respiratory: lungs, trachea, bronchi. Circulatory: heart, blood vessels (arteries, veins, capillaries) and blood.

It coordinates and controls body functions through nerve impulses (brain, spinal cord, nerves).

Regulation of body temperature, blood pressure, blood sugar and pH levels.

The temperature regulating centre signals muscles; shivering generates heat.

The pancreas releases insulin, which lowers blood glucose to normal.

Muscles need more oxygen; faster breathing and heartbeat supply more oxygen and food to the muscles.

It removes wastes and regulates water and salt balance, maintaining blood volume, blood pressure and pH.

The skin acts as a barrier against external factors and regulates temperature through sweating.