MARKING SCHEME

312/1GEOGRAPHYPAPER ONE

KCSE MOCKS 2017

  1. a) what is a planet?

This is a celestial / heavenly body that rotates on its axis and orbit around the sun.

b) Characteristics of planets

They orbit / revolve around the sun

Some have satellites

Each moves on its own orbit

They are at equidistance

  1. a) Main features of the mantle.

Made up of rocks which are fluid /semi solid

The density of rocks range from 3.0 to 3.39m/cc

The rocks are hot with Temperature ranging from 10000c – 30000c

Thickness of 2900km

b) Reasons why the crustal rocks are solid

The crustal rocks are exposed to the atmosphere therefore cool

The crustal rocks are hot under pressure/ no overlying material hence cool

They cooled faster and therefore solidified

  1. a) What is river Rejuvenation

This means renewal of the river’s erosive activities / processes due to Eustatic and dynamic changes

Water will seep from highland to the basin

Wind erosion/ drilling expose the saturated aquifer rocks at the basin and form a well.

Diagram – 1

Explanation – 5

c) (i) parta of the diagram

A – Zone of the non – saturation

B – Zone of intermittent saturation

C – zone of the permanent saturation

(ii) four ways in which

Springs/well as a source of clean water attract human settlement

Underground water is used for industrial and domestic purposes

Geysers/stream jets are harnessed for geothermal production used in industries/ homes

Geysers/hot springs attract tourists

Underground water is used for irrigation in deserts, semi – deserts for agricultural production.

Some hot springs (Spas) are used for medicinal purposes.

b) Four ways in which rivers erode

Through Abrasion / corrosion – where the river uses its load to smoothen

Solution / corrosion where the river solves soluble rock minerals and carries them in solution

Hydraulic where the river exerts pressure in the cracks forcing the rocks to crumble

  1. a) Mts. in East Africa with glaciers

Mt. Kenya

Mt. Kilimanjaro

Mt. Ruwenzori3 max 2 = 2marks

b) Difference between Nunataks and pyramidal peaks

Nunataks are mountain peaks that project through the sheet while pyramidal are glaciated/eroded mt. peaks Mark as a whole 2mks

  1. a) what is Biological weathering

This refers to the disintegration of rocks / breakup of rocks with the influence of living organisms.

b) Block disintegration

This occurs in jointed rocks

Changes in temperate (cooling/heating) makes the rocks to expand and contract

The joints will enlarge

The rocks will break in blocks (rock blocks) hence block disintegration.*(Must be mentioned to score max 3 marks)

SECTION B

  1. a) i) what is a rock?

this is an aggregate of one or more minerals/it is an aggloramation of minerals.

ii) Characteristics of minerals

they have specific colour

they have a luster-ability to reflect light

they vary in hardness

they have specific cleavage-ability to break a long a preferred direction

they have the ability to break (fracture) when not controlled by cleavage

they have specific density

they have different rates of transparency/translucent/opaque

b) i) Rocks marked X, Y, Z

X – Sedimentary rock

Y – Igneous rock

Z – Metamorphic rocks

ii) Why rocks X are common at the coast

the rocks are sedimentary

coastal region is a lowland hence is deposition

coastal is close to the Indian ocean-common marine deposition

c) (i) What is metamorphism?

this is an internal process where the existing rocks are forced to change/transform to new different rocks due to great heat and pressure or both.

(ii) Three processes of metamorphism

thermo metamorphism – great heat due to intrusion of volcanic rocks will force the original rocks to change e.g. sandstone change to quartzite.

Dynamic metamorphism – great pressure due to compression/sheering forces rocks to change to new rocks.

Thermo-dynamic metamorphism- caused by both great heat and pressure to make rocks change s e.g. granite to Gneiss or clay to slate

Meta somatic metamorphism – where hot gases force rocks to change.

(ii) Economic importance of rocks

Some rocks contain vulnerable minerals which are mined and minerals are used for varies purposes by purple

Some rocks like trachyte, elonolite or marble are used by people for building purposes

Some rocks form unique features which attract tourists e.g. granite

Rocks weather/break down to form soil which is used for various agriculture purposes

Some rocks (impermeable) store water as undergroundwater which is used for industrial/domestic purposes.

  1. a) i) What is a desert?

this is a land surface area that is void of/or has minimal vegetation due to insufficient precipitation/minimal rainfall.

ii) Desert surfaces

Reg

Erg

b) i) Reasons why wind is an effective agent of erosion in hot deserts.

winds are strong in hot deserts due to variation of pressure gradients

the absent vegetation makes winds to be more effective

wind is the dominant agent in hot deserts do not exist

iii) Formation of an artesian well.

The acquifer rocks is sandwiched between the impermeable rocks

Due to compression, this rocks and folded to form a basin.

The acquifer rocks are exposed to the surface in the highland where there is rainfall.

c) i) Differences between lapoliths and phacoliths

A phacolith is a sourcer shaped volcanic strata in a syncline while phacolith are horse-shoe shaped lava strata in the anticline

ii) Economic importance of batholiths

Some batholiths are exposed on the earth surfaces as granite rocks which are unique and attract tourists.

Batholiths formation may lead to formation of metamorphic rocks rich in valuable minerals which are mined

When batholiths are exposed on the earth’s surface, they are varried to provide building materials

Batholiths rocks are weathered to form soils used for agriculture.

  1. a) i) What is volcanicity

This is an internal land forming process where gaseous, liquid and solid materials are forced on to the earth surface or into the crustal rocks due to great heat and pressure.

ii) Characteristics of basin lava

they contain 45-52% of silica

it is very fluid

It flows for a long time before they solidify (low viscosity)

It is very mobile.

b) Formation of lava plateaus

formed when ultra-basic lava is extended on the earth surface

the lava is extruded through the cracks or fissure

the basic lava will spread over long distances before it solidifies

successive eruption will from layers of lava that will make the land level/plain

d) i) Use of the hypothesis

it is used as a guide in their research

it is an operational principle for their research

ii) Preparation for fieldworkwith their teacher.

preparation of the objectives/questionnaire

making a pervist/reconnaissance

formation of discussion groups

asking for demission for the head/local administrative

developing a work schedule.

iii) Main problems of field study.

climbing the steep slopes of the rocks

dangers from rock fall

heavy/continuous rainfall disrupted their study

thicket vegetation on the hills slowed down their study

  1. a) i) Climatic region on the map.
  1. Mediterranean climate
  2. Arid/semi arid climate
  3. Tropical climate
  4. Equatorial climate
  5. Warm temperature (mountain)

ii) Characteristics of climate named 5

This is the tropical equatorial climate with the following characteristics;

The region expenses very high rainfall above 1500mm

Rainfall is experienced throughout the year

Rainfall occurs in two maxima’s

Conventional rainfall is common

Temperatures are warm-hot 240-320C

The region experiences low atmospheric pressure

There are weak winds (doldrums)

The area experiences high humidity.

iii) Main factor influenced climate 6.

-altitude

b) How vegetation has adopted in the hot deserts of Namib/Sahara

some plants have long tap roots to reach the deep water table

some have inverted stomata to reduce water loss.

some plants have rough backs to avoid water loss and protection

some trees have succulent trunks/stems/leaves to store water

seeds of some plants remain until when rare rain occurs

some plants are thorny to reduce water loss/protection

some plants/trees are deuduons, most of the year to prevent transpiration

c) i) Water towers in Kenya

Mt. Elgon tower

Mau tower

Abadares tower

Mt Kenya tower

Cherengany tower

ii) Measures the government has taken to conserve forest.

Encouraging people to plant trees

Encourage people to change to agro forestry

Formation of non-governmental groups e.g. green belt group involved in planting trees

Evicting people who have encroached on forest land

Protecting forest reserves

Mass education of importance of forest

Introduction in the education curriculum e.g. forestry as a discipline up to university

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