Practise nervous and endocrine signalling, action potentials, synapses, muscle contraction and plant responses through membrane traces, pathways and structure-function evidence.
The passage outlines the endocrine system.
Complete the passage by using the most appropriate scientific terms.
The endocrine system consists of tissues and ,
which secrete hormones such as insulin, glucagon and antidiuretic hormone (ADH). Glucagon only affects target cells that have complementary receptors, which are located on the . Glucagon binds to these receptors and this leads to the production of a , which transfers the signal throughout the cytoplasm. The target cells for insulin are in the liver, and adipose tissue. The target cells for ADH are those of the distal convoluted tubule and the of the kidney nephron. These hormones are involved in , which is the maintenance of a constant internal environment.
The Venus fly trap is a plant that is able to capture and digest insects. It has modified leaves, which have sensory hairs that respond to touch. When an insect comes into contact with the hairs, receptor potentials are generated.
Name the ion that moves into the cells at the base of the sensory hairs to generate receptor potentials.
If two or more of these hairs are stimulated within a period of 20-35 seconds, action potentials are generated, causing the leaf to close quickly and trap the insect.
Suggest why it is beneficial to the plant for stimulation of two or more hairs to be necessary before the leaf will close.
Outline the differences between the endocrine system and the nervous system.
There are more than 600 plant species in the genus Ipomoea. Many species are grown for their attractive flowers, and some species are used as crop plants.
Scientists are researching whether abscisic acid can be used in crop treatment to increase yield. Evidence suggests that abscisic acid modifies the effect of auxin on elongation growth in plants.
The passage outlines the role of auxin in elongation growth in plants.
Complete the passage by using the most appropriate scientific terms.
The binding of auxin to receptors causes to be pumped into cell walls.
This activates proteins called expansins, which disrupt the links between microfibrils. The cell walls are then able to expand.