Form 2 Science

8/10/2019 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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Documents

Form 2 Science