Specialised cells, tissues and organs

Recall variation between plant cells

A specialised cell is suited to a particular role

A multicellular organism has different types of cells; their shapes and internal structures can suit different functions

Specialisation means having features suited to a particular role; it does not mean a cell is better at every task or has become a separate organism

Explain a link in three steps: identify the feature, state what it allows, then connect that effect to the cell's role

A root hair cell has an extension that increases its surface in contact with soil water; that extra surface supports uptake of water and mineral ions

Connect a root hair with uptake

Connect chloroplasts with light capture

A palisade cell near the upper surface of a leaf contains many chloroplasts

Chloroplasts capture light for photosynthesis

Which link between structure and function is supported?

Chloroplasts capture light for photosynthesis, so many chloroplasts support this role in the leaf; they remain structures within a cell and do not prevent respiration

Many chloroplasts support light capture for making sugars

Different animal cells solve different problems

A muscle cell contains contractile protein structures; their relative movement can shorten the cell and produce a pulling force

A nerve cell can have a long extension along which signals travel; this connects separated regions rather than moving food through a gut

Some airway-lining cells have short beating cilia on their exposed surface; coordinated beating moves mucus containing trapped particles

These records explain selected features rather than listing everything inside each cell; different cell roles do not imply that a cell has no DNA

Connect shortening with movement

Connect an extension with communication

Identify the level from its components

A cell is a basic unit of life; an organelle is a specialised structure within a cell, not an organ

A tissue is a group of cells working together in a shared role; its cells need not all be identical

An organ contains different tissues cooperating in one or more functions; a stomach contains muscle tissue, lining tissue and other tissues

An organ system contains organs working together; the digestive system includes the mouth, stomach and intestines

An organism is the whole living individual; a multicellular organism contains cooperating systems, organs, tissues and cells

Use what a structure contains and how its parts cooperate, not just physical size; an unusually long cell is still a cell

Identify a group of cooperating cells

Identify an organ from different tissues

The stomach contains muscle tissue, lining tissue and other tissues working together

An organ contains different tissues cooperating in one or more functions

Which level describes the whole stomach in this record?

The whole stomach combines different tissues, so it is an organ; the muscle tissue is one component, not the whole stomach

Organ

Apply the organisation to a plant

A leaf contains covering, photosynthetic and transport tissues, so the leaf is an organ rather than one tissue or one chloroplast

In a flowering plant, the shoot system includes stems and leaves, and can include flowers and fruits; the root system includes the roots

A palisade cell belongs to photosynthetic tissue in a leaf; that leaf belongs to the shoot system, which is part of the whole plant

The order is cell, tissue, organ, organ system, organism; this is an organisation of parts, not a claim that each part physically changes into the next one

Classify a leaf using its tissues

Follow a plant's containing relationships

Reveal the links from C to I; C means cell, T tissue, O organ, S organ system and I the individual organism; arrows mean is part of, not physically changes into; positions and circles are symbolic, not anatomical sizes

When every link is shown, what does the arrow from T to O mean?

Specialised parts depend on other parts

Roots take up water and mineral ions; leaves exposed to sufficient light make sugars; transport tissues connect their supplies with other parts of the plant

In an animal intestine, muscle tissue moves contents and lining tissue absorbs nutrients; the organ needs different roles, not every tissue doing the same task

When one structure changes, name its direct functional effect first; keep functions stated to be unchanged separate from possible later effects

Explain cooperation between roots and leaves

Separate changed and unchanged tissue roles

Construct your own linked explanation

Written task for discussion, not automatic marking: a stomach has muscle cells in muscle tissue and several other tissues, and works with the intestines in processing food

Write a chain from one muscle cell to the whole human; name each level, explain how contraction supports a tissue role, and say why the stomach is not just one tissue

Check the links in the explanation

Model: muscle cell, muscle tissue, stomach organ, digestive system, human organism

Contractile structures let muscle cells shorten and pull; cooperating muscle tissue helps mix and move stomach contents

The stomach is an organ because muscle tissue cooperates with lining and other tissue types; the stomach also cooperates with other digestive organs

A complete explanation identifies the components and their roles; stating only that the stomach is bigger than a muscle cell does not justify its level

Connect specialised parts to a whole organism

Link each specialised feature to what it allows and the function it supports

Distinguish organelles within cells from cells, tissues, organs, systems and organisms; use composition and cooperation rather than size

Plants and animals both contain cooperating specialised parts; detailed plant transport and animal digestion build on these relationships