Tissue

In the syllabus and the exam

Tissue sits at the second rung of the 'levels of organisation' ladder tested in the syllabus (cell, tissue, organ, system, organism), and questions often ask candidates to place named structures at the correct level, for example identifying the palisade mesophyll as a tissue while the leaf itself is an organ. Candidates are expected to know both plant tissues (such as xylem, phloem, epidermis and palisade mesophyll) and animal tissues (such as muscle tissue, nervous tissue and epithelial tissue), and to link each tissue's arrangement of cells to the specific job it does, for instance how muscle tissue is built from elongated, contractile cells suited to generating movement. A common mistake is treating 'tissue' and 'organ' as interchangeable, describing the whole leaf, which contains multiple different tissues working together, as 'a tissue' rather than as an organ made of tissues. Another frequent slip is describing a single specialised cell, such as one xylem vessel element or one red blood cell, as a tissue on its own, when a tissue by definition requires a group of similar cells working together, not an isolated cell. Diagrams of a cross-section through a leaf or a blood vessel are commonly used to test whether candidates can correctly identify and label the different tissue layers present. Candidates should also be able to name the specific tissue responsible for a given function described in words, for instance recognising that a description of cells transporting sugars from the leaves to the roots refers to phloem tissue, without the word 'phloem' being given in the question.

Example

Xylem tissue is made up of multiple xylem vessels working together to transport water and mineral salts from the roots to the leaves.

Related terms

CellCell differentiationOrganelle

Source:SRC-DSKP-EN