Spec. Check describe and explain, with the aid of diagrams and photographs, how cells of multicellular organisms are specialised for particular functions, with reference to erythrocytes, neutrophils, epithelial cells, sperm cells, palisade cells, root hair cells and guard cells; explain, with the aid of diagrams and photographs, how cells are organised into tissues, using squamous and ciliated epithelia, xylem and phloem as examples;

Tissues, organs and systems Tissues Squamous epithelial tissue Ciliated epithelial tissue Xylem tissue Phloem tissue Organs Lungs leaf Organ systems Respiratory system Circulatory system

Squamous epithelial tissue Ciliated epithelial tissue Single layer of flat cells lining a surface eg alveoli A layer of cells covered in cilia eg trachea

Which cells transport nutrients? The cells are arranged in plants as vascular bundles. Plants contain two types of cell adapted for transportation. Phloem cells transport sugars produced in the leaves up and down the stem to growing and storage tissues. Xylem cells transport water and minerals up the stem from the roots to the shoots and leaves. This transport occurs in one direction only. Both phloem and xylem form continuous systems connecting roots, stems and leaves.

How is xylem adapted for transportation? Xylem vessels have thick cellulose cell walls, strengthened by lignin. The ends of the cell breakdown so they are continuous. Xylem vessels are dead cells. The thick walls of xylem cells also help support plants. Water and minerals travel in xylem vessels. Parenchyma cells fill the gaps between vessels

Sugars are carried from the leaves to the growing and storage parts of the plants. This movement takes place in both directions. How is phloem adapted to transportation? Phloem is made of columns of living cells. They transport food, in the form of sugars. Phloem cells are also called sieve tubes. Cells are joined by small holes in the cell wall at the end of each cell, forming a continuous system. The end cell walls are called sieve plates. They are associated with companion cells which are very metabolically active.

Organs - a collection of tissues working together Lungs Leaf

Organ systems