Science [5 marks Questions]

Plant Movement
Tropic movement or tropism
Directional movement of specific part of plant in response to external stimuli is called tropism.
These movements are very slow. The movement of plant part can be either towards or away from stimulus.
If the movement of plant is towards stimulus, it is called positive stimulus.
If the movement of plant is away from stimulus, it is called negative stimulus.
1) Phototropism: It is the directional movement of plant part in response to light stimulus.
If plant part move towards light it is called as positive phototropism.
For Ex:Stem or shoot
If plant part move away from light it is called as negative phototropism.
For Ex:Roots
2) Geotropism: It is the response to gravity.
If the plant part moves in the direction of gravity it is called positive geotropism
For Ex:Roots grow downwards.
If the plant part moves against the direction of gravity it is called negative geotropism.
For Ex:Stem grows upwards
3) Chemotropism: Response to chemical stimuli.
If Plant part move towards chemical stimuli it is positive chemotropism
If plant part move away from chemical stimuli it is negative chemotropism.
4) Hydrotropism: Response to water.

a. Reproduction at its most basic level involves making copies of the blueprints of body design. The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body designs.
b. In flowering plants, male gametes are produced in the pollen grains inside the anther. Pollination brings the pollen grains having male gametes from the anther to the stigma. Upon successful arrival of pollen grains on the stigma, a pollen tube is formed where they take male gamete to the female gamete or egg present in the ovule for fertilisation.
c. The body's organs are made of tissue and specialised cells, complex multicellular creatures cannot give birth to new life. Multicellular organisms cannot reproduce by regeneration of a portion of some tissue because of their high level of specialisation.
d. Vegetative propagation is the ability of the plants to reproduce by producing new plants from the vegetative plant parts such as leaf, stem, or roots under appropriate conditions. This method is the only means of reproduction for some seedless plant varieties such as banana, rose, and jasmine.
e. Gametes of sexually-reproducing animals have half the number of chromosomes as that of the parents. Thus, during fertilisation, when two gametes i.e. male and female gametes, fuse, the offspring produced will have the same amount of DNA or the same number of chromosomes as that of the parent.

Detergents are chemically ammonium or sulphonate salts of long chain carboxylic acids. Merits
i. Detergents can work well with both hard water and soft water.
ii. Detergents are more effective than soaps.
iii. Detergents contain synthetic chemicals so tend to provide more cleaning power.
iv. Detergents are made with chemical substances so they can be modified for specific purposes such as laundry detergents etc.
v. Detergents are more easily soluble in water.
Demerits:
i. They are expensive.
ii. They can create water pollution.
iii. Detergents are formed with a synthetic chemical with few natural sources therefore they are usually non-biodegradable.
iv. They can cause soil pollution.
v. Detergent poisoning occurs when someone swallows cationic or anionic detergents, reports Medline Plus.
Detergents are suitable for hard water having Magnesium and Calcium ions because they do not form insoluble salts with these ions.