In multicellular organisms, cells are organized into tissues, organs, and organ systems to perform specialized functions.
Which of the following statements correctly matches a biological structure to its level of organisation and its primary description?
A guard cell is classified as a tissue, composed of pairs of cells with unevenly thickened cell walls that regulate gas exchange through stomatal pores.
Xylem is classified as an organ, consisting of hollow, lignified vessels and fibres that function to transport water and inorganic ions up the stem.
Palisade mesophyll is classified as a tissue, consisting of closely packed columnar cells with high chloroplast density to maximize light absorption.
A leaf is classified as an organ system, containing multiple tissue layers that work together to perform photosynthesis and transpiration.
40 exam-style questions on OCR A A Level Biology Cell division, cell diversity and cellular organisation. Each one has a worked solution and a mark scheme showing where the marks go.