(a) Explain how auxins help in bending of plant stem towards light.
(b) State the objective of the experiment for which experimental set-up is shown in the given diagram.
(a) In plant shoots, the role of auxin is to cause a positive phototropism, i.e. to grow the plant towards the light. When light is incident on a plant from one direction, it causes the auxins to redistribute towards the shaded side of the plant. One function of auxin is to cause cell elongation. The redistribution causes the cells on the shaded side to elongate more than those on the side with the light shining on them. This causes the shoot to bend towards the light.
(b) The objective of the experiment is to show phototropic movement of plant.
Give one example each of a plant part:
(a) which is positively hydrotropic as well as positively geotropic.
(b) which is positively phototropic but negatively geotropic.
What is the name of in-built ‘arrangement’ in our body which controls the timing and amount of hormones released by various endocrine glands in the body ?
A potted plant is made to lie horizontally on the ground. Which part of the plant will show
(i) positive geotropism?
(ii) negative geotropism?
Which one of the following actions on touch is an example of chemical control?
(i) Movement on the touch-sensitive plant.
(ii) Movement in human leg.
Name the plant hormones which are responsible for the following effects :
(a) falling of leaves
(b) opening of stomata
(c) bending of stem towards light (d) closing of stomata
a) What are the short fibres of a neuron known as ?
What is the long fibre of a neuron known as ?
What are the scientific names for the following receptors in animals ?
(a) receptors for light
(b) receptors for heat
(c) receptors for sound
(d) receptors for smell
(e) receptors for taste
Which halogen element is necessary for the making of thyroxine hormone by the thyroid gland ?
(a) Name the hormones secreted by the following endocrine glands :
(i) Thyroid gland (ii) Parathyroid glands (iii) Pancreas (iv) Adrenal glands
(b) Write the functions of testosterone and oestrogen hormones.
Which hormone :
(a) prepares the body for action ?
(b) controls the amount of glucose in blood ?
(c) gives boys a deep voice ?
(d) gives girls soft skin ?
Name the plant hormones responsible for the following:
(a) Elongation of cells.
(b) Growth of stem.
(c) Promotion of cell division.
(d) Falling of senescent leaves.
Answer the following:
(a) Name the endocrine gland associated with brain?
(b) Which gland secretes digestive enzymes as well as hormones?
(c) Name the endocrine gland associated with kidneys?
(d) Which endocrine gland is present in males but not in females?
(a) How is brain protected from injury and shock?
(b) Name two main parts of hind brain and state the functions of each.
(a) Which plant hormone is present in greater concentration in the areas of rapid cell division?
(b) Give one example of a plant growth promoter and a plant growth inhibitor.
State the functions of any three of the structural and functional unit of nervous system.
Name, the two main organs of our central nervous system. Which one of them plays a major role in sending command to muscles to act without involving thinking process? Name the phenomenon involved.
Name one example of the movement of a plant part which is very quick and can be observed easily.
(a) What does a stem (or shoot) do in response to gravity ? What is this phenomenon known as ?
(b) What does a root do in response to light ? What is this phenomenon known as ?
Distinguish between tropic movements and nastic movements in plants. Give examples to illustrate your answer.
(a) What is meant by positive tropism and negative tropism ? Explain with examples.
(b) Define thigmotropism. Give one example of thigmotropism.
(c) What is the difference between thigmotropism and thigmonasty ? Name one plant which exhibits thigmotropism and one plant which exhibits thigmonasty. What behaviour (or responses) of these plants make you think that they exhibit thigmotropism and thigmonasty respectively ?
What is the function of insulin hormone ? What type of patients are given insulin injections ?
When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what the following are examples of :
(a) the smell of the food
(b) the cells in your nasal passages which perceive the smell
(c) the gland which is stimulated to secrete saliva.
(a) Explain any three directional movements in plants.
(b) How brain and spinal cord are protected in human ?
(c) Name the master gland present in the brain.
Which part of the brain controls involuntary actions? Write the function of any two regions of it.
A young green plant receives sunlight from one direction only. What will happen to its shoots ?
(a) Name the two main constituents of the Central Nervous System in human beings.
(b) What is the need for a system of control and coordination in human beings?
(a) Name the two main constituents of the Central Nervous System in human beings.
(b) What is the need for a system of control and coordination in human beings?
Give the scientific terms used to represent the following :
(a) Bending of a shoot towards light.
(b) Growing of roots towards the earth.
(c) Growth of a pollen tube towards ovule.
(d) Bending of roots towards water.
(e) Winding of tendril around a support
Which of the following is a growth movement and which is not ?
(a) folding up of leaves of sensitive plant on touching with hand.
(b) folding up of petals of dandelion flower when light fades.