form 2 science
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CHAPTER : THE WORLD
THROUGH OUR SENCES
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1.1 SENSORY ORGAN
Humans have five sensory organs
SENSE SENSORY ORGAN STIMULUS
TOUCH SKIN TOUCH, PRESSURE,
COLD HEAT , PAIN
SMELL NOSE CHEMICAL
SUBSTANCE IN AIR
HEARING EAR SOUND
TASTE TONGUE CHEMICAL
SUBATANCE IN FOOD
SIGHT EYE LIGHT
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How these sensory organs detects the stimuli?
PRESENCE OF RECEPTOR
PATHWAY FROM STIMULI TO RESPONSE
Nerve impulses are electrical messengers produced byreceptors
Effectors (organs) that carry out response
Responses are reactions received after stimuli.
STIMULI SENSORY
ORGANNERVE BRAIN
RESPONSE NERVEEFFECTORS
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1.2 SENSE OF TOUCH
Our skin has 5 receptors that
are : cold receptor, pressure receptor, pain
receptors, heat receptors and touch receptors
The sensory receptors
depends on:
1) Closeness of receptors
2) Depth of receptors
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1.3 . SENSE OF SMELL
Roof of nasal cavity has many sensory cells to
detect smell
HOW?
1. Cilium contains mucus to dissolve
inhaled particles
2. receptors cell detects smell and
generate nerve impulses
3. Nerves sends nerve impulses to be
interpreted
4. Impulses are sent to the brain
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1.4 . SENSE OF TASTE
Surface of tongue has many taste buds to detect
chemical substance. What are the taste detected by the tongue?
HOW?
1. Chemical particles dissolves in
the saliva on the surface of the
tongue
2. Taste projection receives
stimuli and send it to tastereceptors
3. Taste receptor sets of impulses
4. Impulses sent to the brain to
be interpreted as taste.
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1.5 SENSE OF HEARING
HUMAN EAR
Ear canal
Outer ear: pinna and ear canal
Middle ear: ear drum, ossicles and eustachian tube
Inner ear: semicircular canals, oval window, cochlea andauditory nerve
Oval window
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THE HEARING MECHANISM:
(a) The earlobe collects and directs sound waves into theeardrum through the ear canal.
(b) The eardrum vibrates and the sound vibration intranferred to the ear bones (ossicle).
(c) The ossicles strenghen these vibrations snd conveythem to the oval window.
(d) The vibrations of the oval window cause the fluid in
the cochlea to produce nerve impulses.
(e) The nerve impulses are sent to the brain by theauditory nerve to be interpreted.
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1.6 SENSE OF SIGHT
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1.7.LIGHT AND SIGHT
Reflectionof light happens when it bounce off thesurface on which it falls.
Light rays are reflected by opaque surface
According to the Law of Reflection,
(1) the incident ray, reflected ray and the normal are allon the same plane.(2) the angle of incidence is equal to the angle ofreflection.
The Law of Reflection is obeyed only if the parallel lightrays fall onto a uniform surface.
If the parallel light rays fall on a non-uniform roughsurface, the reflected light rays will not be parallel or inorder but dispersed.
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The characteristics of the image formed are as follows :
(a) virtual ( cannot be formed on a screen ).
(b) vertical.
(c) of the same size as the object.(d) the distance of the image behind the mirror is the same
as the distance of the object in front of the mirror.
(e) laterally inverted.
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Refractionisthe bending of light due to speed change as ittravels through transparent medium.
Refraction of light takes place when light travels through two
different media with different densities at an angle.
The speed of light changes when it moves from one medium
to another with a different density which causes the light to
be refracted (bent).
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1.8. DEFECTS OF VISION
There are 3 types of eye defect:
1) short-sightedness
2)long-sightedness
3) astigmatism
Which of the following are concave and convex lens?
.
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ASTIGMATISM
1.Astigmatism is caused by the irregular curvature of the cornea.
2. All the light rays from an object do not meet at a point on theretina. On the other hand, some light rays are focused on the retina
while others are focused either in front or behind the retina.
3. In many cases, astigmatism causes blurred vision for either near
or distant objects.
4. To correct astigmatism, the optician recommends cylindrical
lenses ( asymmetrical lens ).
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QUESTIONS
What is a blind spot?
What is stereoscopic vision? What is monocular vision?
What are optical instrument?
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1.9. SOUND AND HEARING
Production of Sound
Vibrations produce sound :(a) Sound is a form of energy produced by vibration.(b) When an object vibrates, the kinetic energy from the object is
converted into sound energy.(c) Vibrating objects that produce sound are :
i. Musical instuments such as guitar, voilin and drum when
played.ii. A tuning fork when knocked.iii. Air at the mount of a tube containing water when blown.iv. The tissues in our vocal cords vibrate when we talk.v. Sound produced by animals when their limbs are moved :
- Vibrations of the wings of bees and mosquitoes producesound.
- Grasshoppers produce sound when their hind legh arebrushing against their wings, causing their wings to vibrate.
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Transfer of Sound
1. Sound can be transferred from one place to another through a medium.
2. Sound can move through a solid, a liquid or a gas. Sound is transferred throughthe air when we listen to someone talking.
3. Sound moves fastest through solid, followed by liquid and slowest through avacuum as there are no particles in a vacuum.
Properties of sound:o Produced by vibration,
o Need medium to travel
o Cannot travel via vacuum
o Absorbed by soft and rough surface
o Reflected by hard and smooth surface
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What is stereophonic hearing?
A) hearing by both side of ears
B) hearing by one side of ear
Stereophonic hearing is important to humans and
animals because it can help to determine the
direction or source of a sound. This is importantbecause :
i. It can help avoid danger such as enemies,
predators or moving vehicles.
ii. It can help animals to obtain their food.
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Stimuli and response in plant
What do call the response in plant?
How many types of tropism are there and what are they?
Type of response that plant gives:
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CHAPTER 2: NUTRITION
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2.1 . CLASSES OF FOOD
How many classes of food are there?
What are they?
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Classes of Food- Carbohydrates
- Proteins
- Fats- Vitamins
- Minerals
- Fibre- Water
NUTRIENT SOURCES FUNCTIONS DEFICIENCY DISEASE
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CARBOHYDRATE SUGAR , STARCH,
GLUCOSE
SUPPLY ENERGY TO
THE BODY
BODY LACKS ENERGY
PROTIENS MILK , FISH , EGG,
CHICKEN
-FOR GROWTH
-REPAIR OF BODY
TISSUE
-STUNNED GROWTH,
-KWACHIRKOR
FATS OIL, GHEE,BUTTER -KEEP BODY WARM-TRANSPORT VITAMIN
A, D , E & K
-SUPPLY ENERGY
BODY LACKS ENERGY
FIBRES FRUITS , VEGETABLES HELPS PERISTALSIS &REMOVAL OF
UNDIGESTED FOOD
FROM BODY
CONSTIPATION
WATER FRUITS, VEGETABLES,
DRINKING WATER
-DISSOLVES CHEMICAL
IN BODY
-CONTROLS BODY
DEHYDATION
NUTRIENTS SOURCES FUNCTION DIFICIENCY DISEASE
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(VITAMIN)
A CARROT, FISH LIVER
OIL, GREEN
VEGETABLES
-FOR NIGHT VISION
-HEALTHY SKIN
-NIGHT BLINDNESS
-SKIN INFECTIONS
B MILK, EGG, MEAT,
CEREALS
-HEALTHY NERVOUS
SYSTEM
-FORMATION OF RBC
-BERI BERI
-ANEMIA
C CIRTUS FRUITS,
VEGETABLES
-RESISTANCE TO
DIABETES
- WOUND HEALING
SCURVY
D MADE BY OUR BODY
BY SUNLIGHT, ALSO
PRESENT IN EGG
STRONG BONES AND
TEETH
RICKETS
E NUTS, VEGETABLE OIL,
WHOLE GRAINS
-FOR HEALTHY
REPRODUCTIVE
SYSTEM
-FIGHT AGAINST
DISEASE
STERILITY
K MADE IN HUMAN HELPS BLOOD PROLONGED
NUTRITION SOURCES FUNCTIONS DEFICIENCY DISEASE
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NUTRITION
(MINERALS)
SOURCES FUNCTIONS DEFICIENCY DISEASE
CALCIUM MILK, CHEESE, GREEN
VEGETABLES
-STRONG BONES AND
TEETH
- HEALTHY MUSCLESAND NERVES
-RICKETS
-OSTEOPRIOSIS
-MUSCLE CRAMPS
SODIUM SALT, CHEESE -CONTROLS BODY
FLUIDS
-PROPER
FUNCTIONING OF
NERVES
MUSCULAR CRAMPS
IRON MEAT, GREEN
VEGETABLES, EGGS
FORMATION OF
HAEMOGLOBIN IN
RBC
ANEMIA
IODINE SEAFOODS, IDONIED
SALT
FOE MAKING
HORMONES INTHYROID GLANDS
GOITRE
PHOSPHORUS MEAT, EGG, CHEESE -STRONG TEETH &
BONES
-STORE ENERGY
-RICKETS
-FATIGUE
POTASSIUM MEAT, NUTS PROPER NERVEFUNCTIONING
PARALYSIS
NURTIENTS SOURCES FUNCTION DEFIECENCY DISEASE
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NURTIENTS SOURCES FUNCTION DEFIECENCY DISEASE
FLUORINE DRINKING WATER,
FISH, VEGETABLES
PROTECTS TEETH DENTAL DECAY
Water is needed by the body for:
a. helping in the digestion of food
b. transporting digested food substances
c. transporting excretory products such as urea.
d. maintaining the concentration of blood.
e. maintaining the body temperature
f. all metabolic processes
A balanced diet is necessary for:
a. supplying the required energy
b. balanced body growth
c. maintaining the health of the body
d. preventing deficiency diseases such as scurvy and rickets
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FACTORS THAT INFLUENCE A PERSONS NEEDS
FOR A BALANCED DIET Sex-men required more energy compared towomen of the same age and
body size. men are more active
Age-babies, children and teenagers require more energy compared to adults
or the elderly.
Body size- big-size individuals require more energy size compared to small-
sized individuals
Physical activity-an individual who does heavy work uses more energy
compared to another who does light work
Weather- individuals living in places with cold weather require more energy
compared to individuals living in places with warm weather.
Energy in food measured in joules (J) or calories (cal).
1 calorie (cal) = 4.2 joules (J)
1 kilocalorie (kcal) = 4.2 kilojoules (kJ)
FOOD TEST
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FOOD TEST
NUTRIENTS TEST RESULTS
STARCH (TYPE OF
CARBOHYDRATES)
IODINE TEST BLUE BLACK COLOUR
GLUCOSE (TYPE OF
CARBOHYDRATES)
BENEDICT TEST BRICKED RED PRECIPITATE
PROTIENS MILLIONS TEST RED PRECIPITATE
FATS EMULSIONS TEST MILKY SOLUTIONS
The process of digestion in the alimentary canal:a. physical digestion - involves the mechanical process of breaking
down large pieces of food into smaller particles using the teeth and
the churning movements of the alimentary canal.
b. chemical digestion - involves the action of various enzymes in
breaking down complex
food molecules. These complex molecules are insoluble but the
end products of chemicals digestion are simpler molecules which
are soluble.
HUMAN DIGESTIVE SYSTEM AND THEIR FUNCTIONS
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ABSORPTION OF DIGESTIVE SYSTEM
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ABSORPTION OF DIGESTIVE SYSTEM
Absorption is the process when the end products of digestion enters thebloodstream through the small intestinal walls.
The inner surface of the small intestine (6 metres long) covered with
millions of small projections about 1mm long. These projections are called villi @villus.
Food that has been digested into its most simple form is absorbed by the
villi @ villus on the small intestinal walls into the bloodstream.
The efficiency of absorption of digested food at the small intestine can
be increased by:
a. more villus to increase surface area
b. villus with very thin walls
Each villus has a network of a blood capillaries and a lacteal
Glucose, amino acids, minerals and water-solube vitamins are absorbed
into the blood capillaries.
Fatty acids, glycerol and fat-soluble vitamins (vitamin A, D, E and K) are
absorbed into the lacteal.
REABSORPTION OF WATER AND DEFECATION
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REABSORPTION OF WATER AND DEFECATION The main function of big intestine is to reabsorb water.
The substances that enter the big intestine consist of water and undigested
food substances like cellulose from the fibre of vegetables and fruits(roughage)
Water is reabsorbed from these undigested food substances.
Undigested food materials together with water is passed to the colon(first part
of the large intestine)rectum is the last portion of the large intestine
Undigested food in the big intestine is expelled as faeces through the process
of defecation.
When the rectum is full of faeces, the rectum undergoes peristalsis and
assisted by abdominal contraction, will push the faeces through the anus to be
expelled.
If an individual has problems passing motion, he or she is said to be
constipated.
Constipation takes place because of the lack of water in the diet
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HEALTHY EATING HABITS To eat healthy is important to live healthy life style
EXCESSIVE NUTRIENTS
SUGAR- Diabetes, obesity, tooth decay
SALT AND FATS- high blood pressure, heart attack
LACK NUTRIENTS
FIBRE-CONSTIPATION PROTIEN- KWACHIORKOR
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CHAPTER 3:BIODIVERSITY
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VARIETY OF LIVING THINGS AND
CLASSIFICATION
The living things found on Earth are humans, animals and plants.
A living thing is known as an organism.
Animals and plants have various shapes, sizes and habitats.
The differences that exist between the same species of living
things are called variations.
HABITAT
CLASSIFICATION OF ANIMALS BASED ON
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CLASSIFICATION OF ANIMALS BASED ON
COMMON CHARACTERISTIC
CLASSIFICATION OF PLANTS BASED ON COMMON
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CLASSIFICATION OF PLANTS BASED ON COMMON
CHARACTERISTIC
SYSTEM OF CLASSIFICATION OF ANIMALS
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SYSTEM OF CLASSIFICATION OF ANIMALSAnimals can be classified into two groups :
(a) Invertebrates ( animals without back-bones )
(b) Vertebrates ( animals with backbones )
Invertebrates
1. Invertebrates are animals which do not have backbones.
2. Invertebrates make up the most number of animals in the world.
3. Most invertebrates live in the water.
4. Some invertebrates have a hard external skeleton for protection like the crab
and the beetle.
5. Some invertebrates have soft bodies using their body fluids for support olike
the earthworms
Generally invertebrates can be classified into two groups that is
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Generally, invertebrates can be classified into two groups, that is
(a) with jointed legs (b) without jointed legs
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Vertebrates
Vertebrates are animals with backbones.
Warm-blooded vertebrates ( homoiothermic ) have fixed body
temperatures, cold-blooded vertebrates ( poikilothermic ) have
body temperatures that change according to the temperature of
their surroundings.
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SYSTEM OF CLASSIFICATION OF PLANTS
.
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SYSTEM OF CLASSIFICATION OF PLANTS
FLOWERING PLANTS
This type of plant produces flowers, seeds and fruits.
The flowers normally become fruits.
Flowering plants can be divided into dicotyledons and monocotyledons.
Examples of dicotyledons are rubber trees, durian trees, hibiscus plants and rambutan
trees. Examples of monocotyledons are paddy plant, maize plant, grass and oil palm
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NON FLOWERING PLANTS
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NON-FLOWERING PLANTS Non-flowering plants do not produce flowers, fruits and seeds.
These plants reproduce by spores or binary fission.
Non-flowering plants are divided into four groups, i.e. :(a) algae (c) fungus
(b) moss (d) ferns
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