Which of the following is not an involuntary action?
(a) Vomiting
(b) Salivation
(c) Heartbeat
(d) Chewing
(d) Chewing
Involuntary actions in the body are controlled by
(a) medulla in fore brain
(b) medulla in mid brain
(c) medulla in hind brain
(d) medulla in spinal cord
(c) medulla in hind brain (c) medulla in hind brain Medulla is present only in hind brain
Which of the following statements about transmission of nerve impulse is incorrect? (a) Nerve impulse travels from dendritic end towards axonal end (b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron (c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron (d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells
(b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron Axonal ends, not dendritic ends, are where chemicals or neurotransmitters are released. Therefore, statement b) is false.
The substance that triggers the fall of mature leaves and fruits from plants is due to
(a) auxin
(b) gibberellin
(c) abscisic acid
(d) cytokinin
(c) abscisic acid A layer of abscission is formed by abscisic acid. This layer separates the leaf’s living tissue from the other parts.
The movement of sunflower in accordance with the path of the sun is due to
(a) phototropism
(b) geotropism
(c) chemotropism
(d) hydrotropism
(a) phototropism Phototropism is the movement of a shoot in the direction of light. Geotropism is the term used to describe a plant’s growth in response to gravity. Chemotropism describes a plant’s growth in response to a chemical stimulus. Hydrotropism relates to a plant’s roots growing toward or away from moisture.
The growth of pollen tubes towards ovules is due to
(a) hydrotropism
(b) chemotropism
(c) geotropism
(d) phototropism
(b) chemotropism Pollen tubes grow toward ovules as a result of chemicals released by ovules.
The growth of tendril in pea plants is due to
(a) effect of light
(b) effect of gravity
(c) rapid cell divisions in tendrillar cells that are away from the support
(d) rapid cell divisions in tendrillar cells in contact with the support
(c) rapid cell divisions in tendrillar cells that are away from the support
The shape of guard cells changes due to change in the
(a) protein composition of cells
(b) temperature of cells
(c) amount of water in cells
(d) position of the nucleus in the cells
(c) amount of water in cells Guard cells will become turgid if there is an excess of water, and flaccid if there is a loss of water.
Select the mismatched pair
(a) Adrenaline: Pituitary gland
(b) Testosterone: Testes
(c) Estrogen : Ovary
(d) Thyroxin: Thyroid gland
(a) Adrenaline: Pituitary gland Adrenal gland secretes adrenaline, and pituitary gland produces the hormones TSH, FSH, and GSH.