2019 KCSE Marking Scheme

2019 KCSE General Science paper 1 marking scheme

1. Zoology; RJ wrong spelling.

2. Production of fermented dairy products e.g. yoghurt;

• Production of alcoholic beverages;
• Production of leavened bread;
• Fermented porridge;

3. (i) Diffusion – process by which particles/molecules move from a region of high concentration to a region of low concentration;

(ii) Active transport – process by which particles move from a region of low concentration to a region of high concentration with the use/expenditure of energy;

b) By cells becoming turgid/turgidity;

SECTION B CHEMISTRY

18. (a) Liquid = Solid phase
Temperature remain constant as Kinetic energy reduces, articles, form bonds with each other coming closer to form solids. Energy produced is used in bond formation/ substance is changing state

(b) Solid

19. (a) Noble gases

(b) (i) Atomic Radius Increases downwards due to increase in the number of energy levels.
(ii) Melting point decreases downward the group, the forces of attraction between atoms weakens hence decrease in melting point.

20 (a) Is a substance when in solution/melt conducts and decomposes by passage of an electric current.

(b) Mercury contains delocalized electrons (free electrons) which conduct electricity while Lead (II) bromide in molten state contains IONS (Pb2+, Br) which conduct electricity.

21 (a) Electrons
Protons
Neutrons
Maximum 1 mark : two correct and above

2019 KCSE General Science paper 2 marking scheme

1. a) – Leaves modified into thorns/are needle like to reduce evapotranspiration;

– Succulent stems to store water;
– Deep rooted to absorb water from deep horizons;
– Few stomata to reduce transpiration;
– Sunken stomata to reduce rate of transpiration;
l Have waxy cuticle to reduce rate of respiration;

b) – Suffocation of aquatic animals due to reduced dissolved oxygen levels;
– Rapid growth of aquatic weeds;
– Disease agents in sewage contaminated water;
– Toxic chemicals in sewage kill aquatic organisms;
– Accumulation of heavy metals causing blood poisoning, nervous problems and death;
– Rj pollutes the water alone.

2. a) The production of an off spring as a result of the fusion of a male and a female gamete;

b) Is the duration between fertilization and birth;

3. a) Progesterone; RJ wrong spelling.
b) Repair and healing of the endometrium/ uterine wall;
c) Luteinising hormone (l.H); Rj abbreviations
d) Sperms/ova remain viable in the female reproductive system for
2- 3 days;

4. a) Epigeal germination; RJ wrong spelling.
b) Due to faster elongation of the hypocotyl than the epicotyl the cotyledons and plumule are pushed above the ground;
c) Protects the plumule/Photosynthesis;
d) Exposure of the hypocotyl to light makes auxins to migrate to the lower side; Higher concentration of auxins on the lower side makes the lower sides to grow faster enabling the seedling to straighten;