ks3 science Flashcards
1
Q
organ
A
tissues working together to perform a specific function.
2
Q
organism
A
systems working together as a living thing
3
Q
tissue
A
a group of cells
4
Q
organ system
A
organs working together to perform
5
Q
types of tissues
A
connective tissue, epithelial tissue, muscle tissue, and nervous tissue.
6
Q
muscles
A
-Specialised tissues in the body that are responsible for movement.
-Attached to bones via tendons and can contract and relax
-Muscles work in pairs with one muscle contracting and the other relaxing
7
Q
joints
A
-locations where bones come together.
-responsible for allowing movement in the body.
-Joints can be divided into three categories: fibrous, cartilaginous and synovial.
-Synovial joints are the most common type of joint and are fully movable.
8
Q
tendons
A
-strong, fibrous connective tissues that attach muscle to bones
-responsible for transferring the force generated by muscles to the bone, allowing body parts to move.
9
Q
ligaments
A
-strong fibrous connective tissues that connect bones to other bones at joints.
-provide stability to the joint and help prevent too much movement of dislocation
10
Q
variation
A
there is variation between individuals in a population.
occasionally, new mutations occur which give an advantage.
11
Q
competition
A
-the individuals in a population compete for food, shelter and mates
12
Q
adaptation
A
organisms develop traits or behaviors that enhance their survival and reproduction in a particular environment.
.
13
Q
natural selection
A
the individuals with better adaptations are more likely to survive.
“only the fittest of the fittest shall survive”
14
Q
inheritance
A
when they reproduce, they pass on the alleles for useful adaptation
15
Q
allele
A
An allele is a variant form of a gene.
16
Q
why do living organisms carry out respiration?
A
to release and use energy
17
Q
how is respiration different to breathing?
A
respiration is a chemical reaction that takes place within cells whilst breathing is the exchange of gases in the body.
18
Q
what can the energy released by respiration be used for?
A
movement, growth, cell repair and control of body temp in mamals.
19
Q
Aerobic respiration
A
respiration INVOLVING the use of oxygen
20
Q
equation for aerobic respiration
A
glucose+oxygen->carbon dioxide+water+(energy)
21
Q
anaerobic respiration
A
respiration that doesn’t involve oxygen and usually occurs during strenuous excersise.
22
Q
ANaerobic respiration equation
A
glucose->lactic acid+(energy)
23
Q
anaerobic respiration releases
more/less energy than aerobic respiration
A
less
24
Q
what can build up in the muscles during exercise?
A
lactic acid due to anaerobic respiration, causing cramps.
25
fermentation
type of anaerobic respiration carried out in plant cells and microorganisms like yeast.
26
fermentation equation
glucose-> ethanol+carbon dioxide+ (energy)
27
What is an ecosystem?
An ecosystem is a biological community of interacting organisms and their physical environment.
28
What is a habitat?
A habitat is the natural home or environment of an organism, where it can find food, shelter, protection, and mates for reproduction.
29
What is biodiversity?
Biodiversity refers to the variety and variability of life on Earth, encompassing diversity within species, between species, and of ecosystems.
30
What is a food chain?
A food chain is a linear sequence of organisms where nutrients and *energy* pass as one organism eats another.
31
Can you give an example of a simple food chain?
Grass → Rabbit → Fox
32
What is a food web?
A food web is a complex network of interconnected food chains within an ecosystem
33
What is a producer in an ecosystem?
Producers are organisms that create their own food through photosynthesis
(usually plants and algae) and serve as the base for an ecosystem's energy.
34
What is a consumer in an ecosystem?
Consumers are organisms that cannot produce their own food and need to consume other organisms for energy.
They can be herbivores, carnivores, or omnivores.
35
bioaccumulation
occurs when toxins build up in a food chain
36
What is inheritance?
Inheritance is the process by which genetic information is passed on from parents to their offspring.
37
What are genes?
Genes are segments of DNA that contain the instructions for the development of organisms' traits or characteristics.
38
What is a chromosome?
DNA (deoxyribonucleic acid) is a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms.
39
What is a balanced diet?
A balanced diet includes the right proportions of carbohydrates, proteins, fats, vitamins, minerals, and water necessary to maintain good health.
40
What are the effects of smoking on health?
smoking can cause lung cancer, heart disease, stroke, and respiratory problems. It also increases the risk of various other conditions, including osteoporosis and infertility.
41
What is the role of carbohydrates in the diet?
Carbohydrates are the body's main source of energy.
42
What is the role of proteins in the diet?
Proteins are essential for growth, repair, and maintenance of body tissues.
43
What is the role of fats in the diet?
Fats provide energy, support cell growth, protect organs, and help absorb nutrients. They are found in oils, butter, avocado, and fatty meats.
44
Why is hydration important?
Hydration is vital for maintaining body temperature, removing waste, and lubricating joints. Water is essential for overall health.
45
What are the functions of the circulatory system?
The circulatory system transports oxygen, nutrients, and hormones to cells and removes waste products.
46
What is the role of the heart in the circulatory system?
The heart pumps blood throughout the body, supplying oxygen and nutrients to tissues and removing carbon dioxide and other wastes.
47
What are the main parts of the respiratory system?
The nose, throat (pharynx), voice box (larynx), windpipe (trachea), bronchi, and lungs.
48
How does the respiratory system work?
Air enters the respiratory system through the nose or mouth, travels down the trachea, into the bronchi, and finally into the lungs.
Gas exchange occurs in the lungs, where oxygen is absorbed and carbon dioxide is released.
49
What is the role of the immune system?
The immune system defends the body against infectious organisms and other invaders.
50
What is photosynthesis?
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize nutrients (carbohydrates) from carbon dioxide and water. Oxygen is released as a byproduct.
51
What are the main requirements for photosynthesis?
The main requirements are sunlight, carbon dioxide, water, and chlorophyll.
52
What is the chemical equation for photosynthesis?
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
53
What are stomata?
Stomata are tiny pores found on the surface of plant leaves and stems.
They regulate gas exchange by controlling the intake of carbon dioxide and the release of oxygen and water vapor.
54
How does water enter a plant for photosynthesis?
Water is absorbed by the roots of the plant from the soil and transported through the xylem to the leaves where it is used in photosynthesis.
55
How do plants store excess glucose?
Plants store excess glucose as starch, which can be broken down back into glucose when needed.
56
What is the role of glucose in plants?
Glucose is used by plants as a source of energy for cellular respiration and as a building block for the synthesis of other organic molecules.
57
What is transpiration?
Transpiration is the process by which water evaporates from the surfaces of plant leaves, primarily through the stomata. It helps to pull water up from the roots and is important for nutrient transport.
58
What is the male reproductive system composed of?
The male reproductive system includes the testes, epididymis, vas deferens, seminal vesicles, prostate gland, and penis.
59
What is the function of the testes?
The testes produce sperm and testosterone.
60
What is the female reproductive system composed of?
The female reproductive system includes the ovaries, fallopian tubes, uterus, cervix, and vagina.
61
What is ovulation?
Ovulation is the release of a mature egg (ovum) from the ovary, which typically occurs once a month during the menstrual cycle.
62
What is fertilization?
Fertilization is the fusion of a sperm cell with an egg cell, resulting in the formation of a zygote.
63
What is the menstrual cycle?
The menstrual cycle is a series of monthly changes that occur in the female reproductive system, including ovulation, menstruation, and changes in hormone levels.
64
What is menstruation?
Menstruation is the shedding of the uterine lining (endometrium) that occurs if fertilization does not occur. It is commonly known as a period.
65
What are the reproductive structures of a flower?
The reproductive structures of a flower include the stamen (male reproductive organ) and the pistil (female reproductive organ).
66
What is pollination?
Pollination is the transfer of pollen grains from the male reproductive organ (stamen) to the female reproductive organ (pistil) of a flower, either by wind, insects, birds, or other animals.
67
What is fertilization in plants?
Fertilization in plants occurs when a pollen grain reaches the stigma of a flower and combines with an ovule, leading to the formation of a seed.
68
What are the three states of matter?
solids liquids and gases
69
How do particles behave in a solid?
In a solid, particles are closely packed in a fixed, orderly arrangement and can only vibrate in place
70
How do particles behave in a liquid?
In a liquid, particles are close together but not in a fixed position, allowing them to flow and take the shape of their container.
71
How do particles behave in a gas?
In a gas, particles are far apart and move freely, filling the entire volume of their container.
72
What is density?
Density is a measure of mass per unit volume of a substance.
Density= mass/volume
73
How can mixtures be separated?
Filtration is a method used to separate insoluble solids from liquids using a filter paper and funnel.
74
What is distillation?
Distillation is a process used to separate mixtures based on differences in boiling points. It is used to obtain a pure liquid from a mixture of liquids.
75
What is chromatography?
Chromatography is a technique for separating and identifying mixtures that are or can be colored, especially pigments.
76
What is a chemical change?
A chemical change is a process where substances react and form one or more new substances with different chemical and physical properties.
77
What is a physical change?
A physical change is a change in which no new substances are formed, and only the physical properties (such as shape, phase, or size) of the material change.
78
What are the characteristics of a pure substance?
A pure substance has a fixed composition and distinct chemical properties. It consists of a single type of element or compound.
79
What are the characteristics of an impure substance?
An impure substance consists of two or more types of particles (elements or compounds) mixed together without any chemical bonding between them.
80
How can the purity of a substance be determined?
The purity of a substance can be determined by its melting and boiling points. Pure substances have sharp melting and boiling points, while impure substances melt and boil over a range of temperatures.
81
What is evaporation?
Evaporation is a process where liquid turns into gas at the surface of the liquid, often used to separate a soluble solid from a liquid.
82
How does temperature affect the state of matter?
Increasing temperature generally changes the state from solid to liquid to gas, while decreasing temperature reverses this process.
83
What is a reversible change?
A reversible change is a physical change that can be undone, where the original materials can be recovered.
84
What is an irreversible change?
An irreversible change is a chemical change where new substances are formed, and the original substances cannot be easily recovered.
85
What is an element?
An element is a pure substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom.
86
what is a compound
A compound is a substance made from two or more different elements that are chemically bonded together in a fixed ratio.
87
What is a mixture?
A mixture consists of two or more different substances mingled together but not chemically combined, meaning each substance retains its own chemical identity.
88
How can elements be identified?
Elements can be identified by their unique physical and chemical properties, such as melting point, boiling point, density, and reactivity, as well as by their atomic number in the periodic table.
89
How can compounds be separated?
Compounds can be separated into their constituent elements or simpler compounds by chemical means, such as electrolysis, reactions with other compounds, or heating.
90
What distinguishes a compound from a mixture?
A compound has elements chemically bonded in a fixed ratio and cannot be physically separated, while a mixture contains two or more substances physically combined that can be separated by physical means.
91
Give an example of an element.
Oxygen (O), Carbon (C), Hydrogen (H) are examples of elements.
92
Give an example of a compound.
Water (H₂O), Carbon Dioxide (CO₂), and Sodium Chloride (NaCl) are examples of compounds.
93
Give an example of a mixture.
Air, seawater, and soil are examples of mixtures
94
What is a homogeneous mixture?
A homogeneous mixture is one whose composition is uniform throughout the mixture. examples include solutions like saltwater
They are totally transparent, even if they are coloured.
95
What is a heterogeneous mixture?
A heterogeneous mixture is a mixture in which the composition is not uniform throughout and distinct phases or layers can be observed. Examples include oil and water.
96
How does the boiling point help in separating mixtures?
The boiling point can help in separating mixtures through the process of distillation, where substances with different boiling points are boiled off and re-condensed separately.
97
What is a chemical reaction?
A chemical reaction is a process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.
98
What are the signs of a chemical reaction?
Signs include color change, temperature change, gas production (bubbles), formation of a precipitate, and emission of light.
99
What is a reactant?
Reactants are substances that undergo chemical changes during a chemical reaction.
100
What is a product?
Products are substances that are produced in a chemical reaction from the reactants.
101
What is the law of conservation of mass?
The law states that mass is neither created nor destroyed in a chemical reaction. Therefore, the mass of the products in a chemical reaction must equal the mass of the reactants.
102
What is an exothermic reaction?
An exothermic reaction is one that releases energy to its surroundings, usually in the form of heat.
103
What is an endothermic reaction?
An endothermic reaction is one that absorbs energy from its surroundings, typically as heat.
104
What are catalysts?
Catalysts are substances that increase the rate of a chemical reaction without undergoing permanent chemical change themselves.
105
What is a rate of reaction?
The rate of reaction measures how fast or slow a reaction takes place, often measured by the change in concentration of a reactant or product over time.
106
How can the rate of a chemical reaction be increased?
By increasing the temperature, increasing the concentration of a reactant, increasing the surface area of a reactant, or adding a catalyst.
107
How do you identify an oxidation reaction?
In an oxidation reaction, there is a loss of electrons or an increase in oxidation state by a molecule, atom, or ion.
108
What is an acid?
An acid is a substance that can donate a proton (H⁺) to another substance or accept an electron pair.
-any substance that forms an aqueous solution with a ph of less that 7
109
What is an alkali?
An alkali is a type of base that dissolves in water to form hydroxide ions (OH⁻) in solution, making the solution alkaline.
110
How are acids classified?
Acids are classified as either strong acids, which completely ionize in solution, or weak acids, which only partially ionize.
111
What are the properties of acids?
Acids taste sour, turn blue litmus paper red, and react with metals to produce hydrogen gas. They also neutralize alkalis to form salts and water.
112
What are the properties of alkalis?
Alkalis taste bitter, feel slippery, turn red litmus paper blue, and neutralize acids to form salts and water.
113
What is the pH scale?
The pH scale is a measure of the acidity or alkalinity of a solution, ranging from 0 to 14, with 7 being neutral, values less than 7 indicating acidity, and values greater than 7 indicating alkalinity.
114
What happens when an acid reacts with a metal?
When an acid reacts with a metal, it produces hydrogen gas and a salt. The general equation is: Acid + Metal → Salt + Hydrogen gas.
115
What happens when an acid reacts with a carbonate?
When an acid reacts with a carbonate, it produces carbon dioxide gas, water, and a salt. The general equation is: Acid + Carbonate → Salt + Water + Carbon dioxide.
116
What is a neutralization reaction?
A neutralization reaction is a chemical reaction between an acid and a base (or alkali), resulting in the formation of water and a salt.
117
What is an atom?
An atom is the smallest unit of an element that retains the chemical properties of that element.
118
What are the three subatomic particles of an atom?
The three subatomic particles are protons (positively charged), neutrons (neutral charge), and electrons (negatively charged).
119
Where are protons and neutrons located in an atom?
Protons and neutrons are located in the nucleus of an atom.
120
Where are electrons located in an atom?
Electrons are located in orbitals or electron shells surrounding the nucleus.
121
What is the atomic number of an element?
The atomic number of an element is the number of protons in the nucleus of an atom of that element. It is unique to each element and determines its identity on the periodic table.
122
What is the mass number of an element?
The mass number of an element is the sum of the number of protons and neutrons in the nucleus of an atom of that element.
123
What is an isotope?
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different mass numbers.
124
How many groups are there in the periodic table?
There are 18 groups in the periodic table.
125
What are the elements in Group 1 called? and what are their properties?
-alkali metals
-highly reactive, soft metals that form basic (alkaline)solutions when reacted with water.
-exist as diatomic molecules in their elemental state.
126
what are the elements in group 7 called? what are their properties?
-The elements in Group 7 are called halogens.
-Halogens are highly reactive nonmetals that form acidic solutions when they react with water.
-They exist as diatomic molecules in their elemental state.
127
what are the elements in group 0 called? what are their properties?
-they are called noble gases
-Noble gases are colorless, odorless, and inert (unreactive) gases with low boiling points.
-They have a full outer electron shell, making them stable.
128
what are metalloids?
Metalloids are elements with properties intermediate between metals and nonmetals, located along the staircase line on the periodic table.
129
How is the periodic table organized?
The periodic table is organized into periods (rows) and groups (columns). Elements in the same group have similar chemical properties.
130
what elements are diatomic
Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), and Iodine (I2).
131
what will be produced when acids and alkalis mix together?
a salt and water.
132
what reactions create salts?
-acids and metals
reacting an acid with metal makes two products: a salt and hydrogen.
example: magnesium+hydrochloric cid->magnesium chloride+hydrogen
-acids and bases
reacting an acid with a base also creates salt as well as water.
example: sodium hydroxide+hydrochloric acid-> sodium chloride+water
133
What are the main types of energy stores?
Chemical, kinetic, gravitational potential, elastic potential, thermal, magnetic, electrostatic, and nuclear.
134
What is a system in the context of energy transfers?
A system is an object or group of objects; energy transfers can happen into, out of, or within the system.
135
How is energy transferred between stores in a system?
Energy can be transferred mechanically (by a force doing work), electrically (work done by moving charges), by heating, or by radiation (light or sound).
136
What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transferred from one store to another.
137
What is the formula for calculating kinetic energy (KE)?
KE = 0.5 × mass (kg) × velocity²
138
What is work done in terms of physics?
Work done is the energy transferred when a force moves an object over a distance. Work done = force × distance, or
W=Fd.
139
How do particles transfer energy?
Energy is transferred between particles by heating. In solids, energy is transferred through vibrations of particles in a lattice.
In liquids and gases, energy is transferred by the movement of particles.
140
How is energy transferred by radiation?
Energy can be transferred by electromagnetic waves without the need for a medium, such as the heat from the Sun reaching Earth through the vacuum of space.
141
What is the relationship between energy and temperature?
Increasing the energy of a system generally increases its temperature; the amount of increase depends on the mass of the substance, the type of material, and the energy added.
142
How do we calculate the amount of energy in food and fuels?
The energy transferred can be calculated using the formula: energy = mass of water × specific heat capacity of water × temperature change.
143
What is power in terms of physics?
Power is the rate at which work is done or energy is transferred. It is measured in watts (W).
Formula: power(W)-->energy/ time taken, or
P=J(joules)/t
.
144
What is electric current?
Electric current is the flow of electric charge, measured in amperes (A). It flows from the positive terminal to the negative terminal of a power source.
145
What is potential difference (voltage)?
Potential difference, measured in volts (V), is the difference in electrical potential energy between two points in a circuit. It drives the current around the circuit.
146
Difference between series and parallel circuits.
In a series circuit, components are connected in a single path, so the same current flows through all components.
In a parallel circuit, components are connected across common points or junctions, providing multiple paths for the current.
147
How does resistance affect a circuit?
Resistance, measured in ohms (Ω), opposes the flow of electric current. Higher resistance means less current for a given voltage, according to Ohm's law (V = IR).
148
What creates a magnetic field?
A magnetic field is created by moving electric charges (electric current). Permanent magnets also have magnetic fields due to the alignment of their internal magnetic domains.
149
How does an electromagnet work?
An electromagnet is created by running electric current through a wire coiled around a ferromagnetic core, magnetizing the core as long as the current flows.
150
How can electromagnets be used?
Electromagnets are used in various applications, including electric motors, speakers, and magnetic lifts, due to their ability to turn magnetic force on and off with electricity.
151
How can electricity be generated using electromagnetism?
Electricity can be generated by moving a conductor through a magnetic field or by changing the magnetic field around a conductor, inducing an electromotive force (EMF) in the conductor.
152
How to calculate total resistance in series and parallel circuits?
In series: Total resistance (R_total) = R1 + R2 + R3 + ...
In parallel: 1/R_total = 1/R1 + 1/R2 + 1/R3 + ...
153
How to calculate potential difference using Ohm’s Law?
Potential difference (V) = Current (I) × Resistance (R).
154
Explain the process of electrons transferring to your hair when rubbing a balloon against it.
When you rub a balloon against your hair, electrons are transferred from your hair to the balloon (or vice versa, depending on the materials) due to friction. This leaves the balloon negatively charged and your hair positively charged, causing an attractive force between them due to the difference in charges.
155
What is speed and how is it calculated?
Speed is the rate of change of distance over time, calculated as speed = distance ÷ time. Its SI unit is meters per second (m/s).
156
How do you interpret distance-time graphs?
A flat section represents stationary objects. A straight uphill section indicates constant speed. The steeper the graph, the faster the motion. A curve indicates acceleration.
157
How do you interpret velocity-time graphs?
A flat section indicates constant velocity. Uphill shows acceleration, while downhill shows deceleration. The steeper the slope, the greater the acceleration. The area under the graph represents the distance traveled.
158
What is pressure and how is it calculated in gases?
Pressure is the force exerted per unit area. In gases, pressure is caused by moving molecules colliding with container walls. It's calculated as pressure = force ÷ area, with units of Pascals (Pa).
159
How does pressure in solids work?
Pressure in solids depends on the force applied and the area over which it's applied. A smaller area under the same force results in higher pressure, which explains why sharp knives cut better than dull ones.
160
How is pressure calculated in liquids and what is Pascal’s law?
Pressure in liquids is calculated as pressure = height × density × gravity. Pascal's law states that pressure applied to an enclosed fluid is transmitted uniformly in all directions.
161
What are turning forces and how do they work?
Turning forces or moments are caused by applying a force at a distance from a pivot. The moment of force = force × distance from pivot, influencing how effectively a force can cause an object to rotate.
162
Explain squashing and stretching forces.
Squashing and stretching involve compressive and tensile forces, respectively. Squashing forces reduce the length or volume of an object, while stretching forces increase it. These are crucial in structures and materials testing.
163
What are drag forces and friction?
Drag forces and friction resist motion. Drag is a resistance force by air or liquid against the direction of an object's movement. Friction is the resistance encountered when two surfaces slide past each other.
164
How do forces act at a distance?
Forces like gravity and magnetism can act at a distance, meaning they exert an influence without physical contact. For example, gravitational force keeps planets in orbit around the sun.
165
What distinguishes balanced and unbalanced forces?
Balanced forces act on an object without causing a change in motion, keeping it stationary or moving at a constant speed. Unbalanced forces cause an object to start moving, stop, or change direction.
166
How do pressure and area relate to force?
The pressure applied to an object or surface is inversely proportional to the area over which the force is distributed.
For a given force, smaller areas result in higher pressure.
167
Explain how the design of a car reduces drag forces.
The design of a car reduces drag forces through streamlining, allowing air to flow smoothly over and around the body, minimizing resistance and improving fuel efficiency.
168
How does the depth of a liquid affect pressure?
The pressure in a liquid increases with depth due to the weight of the liquid above exerting a force on the liquid below, calculated as pressure = depth × density × gravitational field strength.
169
What are waves and how do they transfer energy?
Waves are disturbances that transfer energy from one place to another without transferring matter. In sound waves, energy is transferred through vibrations of particles in a medium. In light waves, energy is transferred through electromagnetic fields in both mediums and vacuum.
170
How does sound travel through different mediums?
Sound travels as a series of compressions and rarefactions in a medium (solid, liquid, or gas). It travels fastest in solids, slower in liquids, and slowest in gases because the particles are closer together in solids, facilitating quicker energy transfer.
171
What determines the loudness and pitch of a sound?
Loudness is determined by the amplitude of the sound wave; larger amplitudes make louder sounds. Pitch is determined by the frequency of the sound wave; higher frequencies produce higher pitches.
172
How do humans detect sound?
Humans detect sound through the ear, which converts vibrations of air particles into signals that the brain interprets as sound. The outer ear collects sound waves, the middle ear amplifies them, and the inner ear converts them into electrical signals.
173
What are echoes and how are they used in ultrasound?
Echoes are reflections of sound waves off surfaces. Ultrasound uses echoes to create images of internal body structures. High-frequency sound waves are sent into the body, and the echoes that return are used to construct an image.
174
How does light travel and interact with materials?
Light travels as electromagnetic waves and can be reflected, refracted, or absorbed by materials.
Reflection occurs when light bounces off a surface, refraction occurs when light changes direction entering a different medium, and absorption happens when the energy of light is taken up by the material.
175
What is the law of reflection?
The law of reflection states that the angle of incidence (the angle at which light hits a surface) is equal to the angle of reflection (the angle at which light bounces off the surface), measured from the normal (a perpendicular line to the surface).
176
How does refraction occur, and what is Snell's law?
Refraction occurs when light waves change speed as they pass from one medium to another, causing the light to change direction.
Snell's law describes this effect, relating the angle of incidence and refraction to the indices of refraction of the two media.
177
How do the eye and the camera work similarly in focusing light?
Both the human eye and cameras focus light to create clear images.
The eye uses the cornea and lens to focus light onto the retina, much like a camera uses lenses to focus light onto film or a digital sensor. Both adjust focus by changing the shape of the lens or adjusting lens positions.
178
How is colour perceived by the human eye?
Colour is perceived by the eye's response to different wavelengths of light. The retina contains photoreceptors (cones) sensitive to red, green, and blue light. The brain interprets signals from these cones to perceive a wide range of colors.
179
What are the primary colors of light?
The primary colors of light are red, green, and blue. When combined in various ways, they can produce a wide spectrum of colors, including the secondary colors: cyan, magenta, and yellow.
180
What causes the different phases of the Moon?
The phases of the Moon are caused by the changing positions of the Earth, Moon, and Sun, affecting how much of the Moon's surface is illuminated and visible from Earth.
181
What are constellations, and why do they appear to change throughout the year?
Constellations are patterns of stars in the night sky. They appear to change due to Earth’s orbit around the Sun, changing our perspective on the stars.
182
What are the main components of the Solar System?
The Solar System consists of the Sun, eight planets, their moons, dwarf planets, asteroids, and comets.
183
How does the mass of a planet affect its gravitational pull?
The greater the mass of a planet, the stronger its gravitational pull. This is why objects weigh more on larger planets like Jupiter compared to Earth.
184
What is the difference between a comet and an asteroid?
Comets are composed of ice, dust, and rocky material and often have a visible coma (a fuzzy outline and a tail) when they approach the Sun.
Asteroids are made of metals and rocky material and do not exhibit comas or tails.
185
Why does the Earth experience seasons?
The Earth experiences seasons due to its axial tilt. As the Earth orbits the Sun, its tilted axis means different areas of the Earth receive more direct sunlight at different times of the year.
186
What causes a solar eclipse?
A solar eclipse occurs when the Moon passes directly between the Earth and the Sun, casting a shadow on the Earth and partially or fully blocking the Sun's light in some areas.
187
What causes a lunar eclipse?
A lunar eclipse happens when the Earth passes directly between the Sun and the Moon, and the Earth's shadow falls on the Moon, making it appear reddish-brown.
188
How do tides work, and what role does the Moon play in them?
Tides are caused by the gravitational pull of the Moon and the Sun on the Earth's oceans. The Moon's gravity causes the water to bulge out on the side closest to the Moon and the opposite side, leading to high tides.
189
how to test for lipids
because fats and oils are insoluble in water, they are dissolved in ethanol.
If fat is present, it will form a cloudy solution.
190
how to test for starch
starch is the storage molecule for plants and are found in foods that are made of plant tissue.
When iodine/ potassium iodide solution is mixed, it changes from brown to dark blue. This happens when starch is present.
191
How do you test for glucose in a solution?
the presence of glucose can be identified with Benedict's reagent. The pale blue benedict solution is added to a prepared sample, heated up to 95 degrees.
If it changes colour or forms precipitate (solid formed by a change in solution), this indicates its presence.
If the solution turns green, this shows that a small amount of glucose is present. If it turns bright orange/ red, a lot of glucose is present.
192
What are lipids important in?
forming cell membranes and many other molecules in the body such as fats in storage cells.
193
what are the basic units of lipids, proteins and carbohydrates?
fatty acids and glucose
amino acids
simple sugars
194
how do you test for protein in a solution
The biuret test is used.
If the sample of food contains protein, a blue ring appears on the surface of the water.
If the sample is shaken, the solution turns bright purple.
195
difference between plant and animal cells
Plant cells have a rigid cell wall made of cellulose, while animal cells lack this structure.
Chloroplasts, responsible for photosynthesis, are present in plant cells but absent in animal cells.
Plant cells often contain large central vacuoles, which help maintain turgor pressure, while animal cells may have smaller vacuoles or lack them altogether.
Animal cells typically have centrioles, which play a role in cell division, while plant cells do not.
Plant cells may contain plastids, such as chromoplasts or amyloplasts, which are absent in animal cells.
Lysosomes, responsible for cellular waste management, are more prominent in animal cells compared to plant cells.
Plant cells usually have a regular, rectangular shape due to their rigid cell walls, while animal cells tend to be more irregular in shape.
Mitochondria, the powerhouse of the cell, are present in both plant and animal cells.
196
How does gas exchange occur in fish?
Gas exchange in fish occurs through gills, where water flows over gill filaments rich in blood vessels, allowing oxygen to be absorbed and carbon dioxide to be expelled directly into the water.
197
What is gas exchange?
Gas exchange is the biological process by which organisms exchange oxygen and carbon dioxide with their environment.
In humans and other animals, this occurs in the lungs or gills, facilitating the intake of oxygen for cellular respiration and the expulsion of carbon dioxide.
198
Where does gas exchange occur in humans?
Gas exchange in humans occurs in the alveoli, small air sacs in the lungs.
199
What is the primary purpose of gas exchange in the respiratory system?
The primary purpose is to oxygenate blood and remove carbon dioxide from the body.
200
How does oxygen move from the alveoli into the blood?
Oxygen moves from the alveoli into the blood through the process of diffusion, moving from an area of higher concentration in the alveoli to a lower concentration in the blood.
201
Why is carbon dioxide exchanged for oxygen in the lungs?
Carbon dioxide is exchanged for oxygen in the lungs because it is a waste product of cellular respiration and needs to be expelled from the body, while oxygen is needed for cellular respiration to produce energy.
202
What role do hemoglobin molecules in red blood cells play in gas exchange?
Hemoglobin molecules bind to oxygen in the lungs, allowing oxygen to be transported through the blood to tissues and organs.
Hemoglobin also helps in transporting carbon dioxide back to the lungs for exhalation.
203
v
