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DGS S2 Science > Sensing The Environment (10.1-10.3, 10.7) > Flashcards

Sensing The Environment (10.1-10.3, 10.7) Flashcards

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1
Q

What is sensitivity?

A

Sensitivity is the ability to detect and respond to stimuli, which are changed in the environment that causes a response.

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2
Q

In what ways are sensitivity important for the survival of living things?

A

Sensitivity can help organisms escape from danger, search for food, amd find mates.

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3
Q

How are senses produced?

A

The stimuli are detected by specilaised sensory cells in sense organs, and signals are sent to the brain through nerves, producing senses.

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4
Q

What are all of our senses and sense organs?

A

Sense organs: eyes, ears, nose, mouth, skin

Senses: sight, hearing, smell, taste, touch

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5
Q

What is the purpose of the eyebrow?

A

It prevents sweat from getting into our eyes.

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6
Q

What is the purpose of the eyelashes?

A

They prevent small particles such as dust, from getting into our eyes.

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7
Q

What is the purpose of the eyelid?

A

It can blink to moisten the eye surface and protect the eye from strong light and dirt.

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8
Q

What is the purpose of the cornea?

A

It lets light pass through and helps to focus light.

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9
Q

What is the purpose of the iris?

A

It controls the size of the pupil.

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10
Q

What is the purpose of the focusing muscles?

A

They help to change the thickness of the lens.

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11
Q

What is the purpose of the lens?

A

It lets light pass through and helps to focus light.

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12
Q

What is the purpose of the pupil?

A

It regulates the amount of light entering the eye.

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13
Q

What is the purpose of the jelly-like fluid?

A

It helps to hold the shape of the eyeball and focus light.

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14
Q

What is the purpose of the sclera?

A

It protects the eyeball.

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15
Q

What is the purpose of the retina?

A

It has light-sensitive cells on it that detect light and produce signals.

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16
Q

What is the purpose of the optic nerve?

A

It sends the signals produced by light-sensitive cells to the brain.

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17
Q

What is the blind spot?

A

It is where the optic nerve leaves the retina. There are no light-sensitive cells in the blind spot.

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18
Q

How does the size of the pupil change when exposed to light of different brightness?

A

In bright light, the pupil becomes smaller to decrease the amount of light entering the eye. In dim light, it becomes larger to increase the amount of light entering the eye.

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19
Q

How is an image formed in the eye?

A

The light enters our eye through the cornea. The cornea, lens, and jelly-like fluid help focus the light onto the retina. Then, a sharp and inverted image will be formed on the retina. The light-sensitive cells are stimulated by the light and they produce signals. The brain interprets the signals sent as an upright image.

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20
Q

Describe the image formed on the retina.

A

It is inverted, both upside-down and left-to-right.

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21
Q

Which type of lens are used to focus light from a near and distant object respectively?

A

A thick convex lens is needed to focus light from a near object. A thin convex lens is needed to focus the light from a distant object.

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22
Q

How can the human lens change in thickness to let us focus light from different distances?

A

The lens is elastic. The focusing muscles contract to make the lens thicker and relax to make the lens thinner.

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23
Q

Name the two types of light-sensitive cells on the retina and their uses.

A

Cone cell: works well in bright light, can distinguish colours
Rod cell: works well in dim light, cannot detect colour

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24
Q

What are limitations of the human eye?

A

We cannot see objects that are too close, too far away, or too small. Also, we cannot see images formed on the blind spot.

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25
Q

List 5 optical instruments used to help extend our vision.

A

binoculars, light microscope, electron microscope, astronomical telescope, hand lens

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26
Q

List 5 common eye defects.

A

Short sight, long sight, astigmatism, cataract, colour blindness.

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27
Q

What happens if you have short sight?

A

You cannot see distant objects clearly because the images are formed in front of the retina.

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28
Q

What is the cause of short sight?

A

Short sight is caused by the lens being too thick, the eyeball being too long, or both.

29
Q

What happens if you have long sight?

A

You cannot see near objects clearly because the images of near objects are formed behind the retina.

30
Q

What is the cause of long sight?

A

Long sight is caused by the lens being too thin, the eyeball being too short, or both.

31
Q

How can we correct short sight and long sight?

A

Short sight: wear glasses with concave lens

Long sight: wear glasses with convex lens

32
Q

What happens if you have astigmatism or cataract?

A

You have blurred vision.

33
Q

What is the cause of astigmatism?

A

Astigmatism is caused by the cornea or lens being unevenly curved.

34
Q

How can we correct astigmatism?

A

Wear glasses with lenses that have different curvatures at different points.

35
Q

What is the cause of cataract?

A

If you have cataract, your lens becomes cloudy. This may be caused by eye injuries, prolonged exposure to sunlight, heredity, or old age.

36
Q

How can we correct cataract?

A

Replace the cloudy lens with an artificial lens through surgery.

37
Q

What is colour blindness and what are its causes?

A

Colour blindness affects a person’s ability to distinguish colours correctly, and it is caused by the defect of one or more types of cone cells.

38
Q

Why do people have colour blindness and how can it be corrected?

A

Colour blindness is an inherited defect and it cannot be corrected.

39
Q

How is sound produced?

A

Sound is produced through the vibration of objects.

40
Q

What is frequency and what unit is ised to measure it?

A

Fequency measures the number of vibrations an object makes in a second. It is measured in hertz.

41
Q

How is frequency related to pitch?

A

The hugher the frequency, the higher the pitch.

42
Q

Explain the process through which sound is transmitted for us to hear.

A

When an object vibrates, it pushes on the air particles nearby and set them into vibration. Therefore, more and more air particles are set to vibration and the sound is transmitted.

43
Q

Can sound travel through solids and liquids?

A

Yes, sound can travel through both solids and liquids.

44
Q

Can sound travel in a vacuum? Why?

A

No, sound cannot travel through a vaccum, because there are no air particles in a vaccum to vibrate and transmit the sound.

45
Q

What is necessary for sound to travel?

A

A medium (media in plural)

46
Q

Compare the speeds of sound when travelling through gases, liquids, and solids with explanation.

A

Sound travels the fastest in solids, followed by liquids and gases. This is because the particles of solids are more densely packed than the particles or other forms matter, letting vibrations travel quickly.

47
Q

Which sections can the human ear be divided into?

A

Outer ear, middle ear, inner ear

48
Q

What is the purpose of the pinna?

A

The pinna located in the outer ear has a funnel shape, allowing it to collect sounds from the surroundings amd direct the sound into the ear canal.

49
Q

What is the purpose of the ear canal?

A

Sound travels through the ear canal to the middle ear.

50
Q

What is the purpose of the eardrum?

A

The eardrum vibrates when sounds comes in and the vibrations are transmitted to the ear bones.

51
Q

What is the purpose of the ear bones?

A

They amplify the vibrations of the eardrum and transmit them into the inner ear.

52
Q

What is the shape of the cochlea?

A

It is coiled.

53
Q

What is the purpose of the cochlea?

A

The cochlea contains sensory hair cells inside which can detect vibrations and send signals.

54
Q

How are the signals from the sensory hair cells sent to the brain?

A

They are sent through the auditory nerve and the brain interprets them as sound.

55
Q

How does sound travel through our ears?

A

Sound enters the ear through the pinna. Then, it is directed to the middle ear through the ear canal. The sound causes the eardrum to vibrate. Then, the ear bones amplify the vibrations. The sensory hair cells in the cochlea then detects the vibrations and produce signals. The signals are sent to the brain through the auditory nerve.

56
Q

What is the limitation of our ears?

A

The average human ear can hear sounds from approximately 20Hz to 20, 000Hz. The sounds that have frequency beyond the audible frequency range cannot be heard.

57
Q

List two applications of ultrasound.

A

Checking for cracks in pipes, and checking the condition of a foetus

58
Q

Which tool is used to measure the loudness of sounds? What is its unit?

A

Decibel meter,it measures sounds in decibels (dB).

59
Q

What is the range of loudness of noise that may cause hearing problems for humans?

A

Noise exceeding 85dB

60
Q

What are possible effects of being exposed to loud noise for long periods of time?

A

The noise will cause disturbance to our work, study, or sleep. It can also cause mental stress, tinnitus, or hearing loss.

61
Q

How can we protect our sense of hearing?

A

Keep the volume low when listening to music using earphones and shorten the time we stay in a noisy environment. If exposure to loud noise is unavoidable, we should wear earplugs or ear protectors. We should not pick our ears with hard objects.

62
Q

What is noise?

A

Unwanted/disturbing sound

63
Q

What is the role of our brain?

A

Our brain receives the signals of stimuli from sense organs through nerves. It integrates and inteprets the signals received from different sense organs and produces senses. Then, it decides on actions, and sends signals to muscles through nerves to make a response.

64
Q

What is reaction time? Can it be changed?

A

The time between detecting a stimulus and making a response. It can be improved after practice.

65
Q

Describe the form and number of nerve cells in our brain.

A

We have over 10 billion nerve cells in our brain. They have long extensions and connect to each other, allowing signals to be sent.

66
Q

What is the function of the medulla?

A

The medulla controls basic involuntary life functions, such as breathing, heartbeat, and blood pressure.

67
Q

What is the function of the cerebrum?

A

The cerebrum integrates and interprets the signals sent from sense organs, and sends signals to muscles. It is responsible for intelligence, memory, and thinking.

68
Q

What is the function of the cerebellum?

A

The cerebellum coordinates muscle movement and is responsible for balance.

69
Q

Why do illusions take place?

A

Illusions form when the brain interprets signals wrongly.

DGS S2 Science (5 decks)

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