Tissues in Action: questions with answers

A tissue is a group of cells similar in structure that work together to do one particular function. Different tissues do different jobs, which gives division of labour in the body.

Specialised tissues share work rather than requiring every cell to do everything. Their coordinated functions permit complex processes.

Lateral meristem adds cells that increase stem girth. Actively dividing meristematic cells lack vacuoles. Differentiation produces specialised permanent cells and is associated with loss of division ability.

Removing the apical meristem stops continued length growth of that root in this experiment. Meristems also occur at other tips, along stems and near certain nodes.

Collenchyma provides flexible support through living cells with unevenly thickened walls. A thick cuticle reduces water loss and is especially useful in dry habitats. Sclerenchyma provides rigid strength.

Most sclerenchyma cells are dead and their walls are thickened with lignin, which makes the tissue hard and strong. Parenchyma stays living with thin walls, so it stores food. Pectin thickening at the corners belongs to collenchyma, not sclerenchyma.

Separate vertebrae form a flexible column, and cartilage discs cushion between them. This arrangement supports the body and protects the spinal cord.

The ribs protect the heart and lungs, yet flexible cartilage connections allow breathing movement. Strength and controlled flexibility work together.

Sieve tubes conduct food in phloem. Companion cells support their functioning, and phloem also contains parenchyma and fibres. Xylem carries water and minerals rather than food.

Xylem carries water and minerals, while phloem carries food. Each contains several cell types. Xylem parenchyma is living, so living cells occur in both tissues.

Totipotency is expressed only under suitable culture conditions. The mature cell must regain division ability and then form specialised plant parts.

A mature cell first regains the power to divide. It then divides again and again to form a mass of cells. These cells later grow into organised roots and shoots, giving a whole plant. This needs nutrients and controlled conditions.

A single thin layer gives gases a short distance to cross. Thick layers suit protection, while ciliated cells move material along a surface.

Skeletal muscle moves when we choose, through messages from nerves. Smooth muscle in the gut and cardiac muscle in the heart work without our will. Cardiac muscle is striated, yet it is still involuntary.

Muscles pull on bones through tendons. The elbow is a hinge joint that mainly permits bending and straightening. The shoulder allows movement in many directions.