bio 🌱🪸 Flashcards
practice questions and notes
1
Q
what are life processes
A
These are the 7 signs of life that most living organisms show in their life.
2
Q
what are the seven life processes?
A
movement, growth, respiration, reproduction, excretion, sensitivity and nutrition.
3
Q
whats an example of an organism that only moves parts of its body?
A
Plants move parts of their structures in response to external stimuli such as light
All structures in the cytoplasm of all cells move.
4
Q
what is respiration?
A
a series of chemical reactions inside living cells that breaks down nutrient molecules and releases energy.
5
Q
what are all chemical reactions that help to keep the body alive called?
A
metabolic reactions, powered by energy released from metabolic reactions
6
Q
what is sensitivity in living organisms?
A
It is the ability to detect and respond to changes in the environment around them.
living organisms can also respond and sense to changes inside their bodies (internal environment)
7
Q
Explain growth
A
this is the permanent increase in size of an organism. An organism changes in size when nutrients are taken into the cells and used to increase their number and size.
Growth is measured in terms of dry mass (mass without water content) because when growth is measured it should exclude temporary changes due to how much the organism eats or drinks.
8
Q
What is reproduction
A
This results in more individuals of that kind of organism being produced. This involves producing gametes and the fertilisation of these gametes.
9
Q
What is excretion
A
This is the removal from the body of substances that are toxic and may damage cells if they stay in the body.
Organisms also excrete substances that are in excess.
10
Q
what happens to waste products of metabolic reactions in cells
A
These are also excreted. For example, animals produce carbon dioxide during respiration. This cannot be used and is excreted.
11
Q
Nutrition
A
This is the absorption of nutrients into the body.
These are the raw materials needed by the the cells to release energy to make more cells for growth, development and repair.
12
Q
how is nutrients required for plants and animals different
A
Plant nutrients include light, carbon dioxide, water and mineral ions.
Animal nutrients include organic compounds such as carbohydrates, proteins ,mineral ions such as iron and sodium as well as water.
13
Q
What are the two live processes necessary for an organism to release energy?
A
respiration and nutrition.
14
Q
when you place a crystal of copper sulfate in a saturated solution of the same compound, the crystal will increase in size. Does this mean that the crystal is alive?
A
This does not mean that it is alive as internally, processes are not being carried for this growth and increase in size to happen.
15
Q
what are cells?
A
all living organisms are made of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialised functions.
16
Q
what cell structures exist in all cells?
A
the cytoplasm and cell membrane
17
Q
cell structures of animals vs plants
A
Both animal and plant cells have: cell membrane, mitochondria, nucleus, cytoplasm
only plant cells contain: chloroplasts, large vacuole and cell wall.
18
Q
what are unicellular organisms w/examples
A
organisms that are comprised of only one cell. e.g fungi, bacteria and protoists.
19
Q
cell membrane
A
holds the cell together and controls what enters and exits the cell.
20
Q
cytoplasm
A
supports small structures. Many chemical reactions happen. Contains water with various solutes dissolved in it.
21
Q
nucleus
A
contains genetic material in chromosomes. These control how cells grow and function. They also control all cell division.
22
Q
cell wall
A
made of cellulose- maintains cells shape and gives extra layer of support.
23
Q
large vacuole
A
made of cell sap- used for storage of materials. It also supports the shape of a cell. If there isn’t enough cell sap in vacuole, plants start to wilt.
24
Q
chloroplast
A
contains a green pigment called chlorophyll which absorbs light energy in order for the plant to make energy.
25
cell specialisation
different types of cells carry out different tasks. They have different features to help them carry out these tasks.
26
what are some examples of specialised cells?
ciliated cells, palisade mesophyll cells, red blood cells, human sex cells and rot hair cells.
27
ciliated cells (how are they specialised)
tiny hair like projections which cover the surfaces of certain types of cells.
Cilia can move and the cell can coordinate this movement to produce waves which can move liquids in certain directions.
28
whats the purpose of ciliated cells in the respiratory tract?
They move a liquid called mucus.
Along with tiny particles of dust or bacteria that are trapped in the mucus, mucus passes up the tubes and is emptied through the oesophagus where it is swallowed and passes into the stomach.
Ciliated cells keep the lungs clean.
29
What are palisade mesophyll cells (how are they specialised)
They are plant cells which are found in the upper part of the leaf. These cells contain many chloroplasts in order to carry out photosynthesis.
30
red blood cells (how are they specialised)
RBCs are specialised for carrying oxygen around the body.
They are not able to undergo cell division as they don't have a nucleus. This maximises surface area for oxygen to be carried in.
They are filled with a chemical called haemoglobin which picks up the oxygen in the lungs and releases it near cells that need it in the body.
diffusion of oxygen happens easily and rapidly.
RBCs are made in bone marrow and only last around 120 days before being destroyed in the spleen & liver.
31
what are the human sex cells
Human sex cells, otherwise called gametes, are the sperm cell and the egg cell.
32
how are sperm cells specialised
sperm cells are small in comparison to an egg cell.
They have very little cytoplasm surrounding the nucleus because they carry our few functions other than travelling to the egg.
There is a small vesicle of enzymes at the front tip of the cell called the acrosome. The enzymes digest a hole in the egg cell membrane. This allows the nuclei of the sperm and egg cell to fuse.
sperm cells also contain a lot of mitochondria which provide sufficient energy to move the tail (flagellum), which powers the sperm towards the egg cell.
33
the egg cell (how is it specialised)
The egg cell is much larger than the sperm cell and cannot move on its own.
The large amount of cytoplasm around the nucleus provides nutrients for when the cell is fertilised and starts to divide.
34
root hair cells (how are they specialised and what are they)
In many plants, water and minerals are absorbed by root hairs which penetrate the spaces between soil particles.
These hairs are very fine extensions of the root hair cells of the roots surface, just behind the growing tip of the root.
The elongated shape increases the surface area of the absorption of water and dissolved mineral ions.
As they age, these cells develop a waterproof layer making them dysfunctional. New root hairs constantly grow as the root pushes through the soil.
35
what is diffusion (bio)
It is the net movement of particles from a region of high concentration to a region of low concentration.
This difference of concentration is what makes it happen. Particles tend to "move down the concentration gradient" (movement of molecules from a high concentration area to a low concentration area)
This happens because of the random movement of particles.
36
explain diffusion in cells.
Cells are surrounded by cell membranes which are leaky and let tiny particles pass through them.
However large particles cannot get through, making the PARTIALLY PERMEABLE.
Movement of particles across a cell membrane differ according to the difference of concentration in each side.
e.g In the blood vessels of the lungs there is a low oxygen concentration inside the red blood cells and high oxygen concentration in the alveoli of the lungs. Therefore, oxygen diffuses from the alveoli into the red blood cells.
37
what are some other examples of diffusion in biology?
carbon dioxide entering leaf cells
digested food substances from the small intestines entering the blood.
38
Does diffusion require any energy from the cell?
no, it is a passive process.
39
what is osmosis
The diffusion of water molecules from a region of higher concentration to lower concentration through a partially permeable membrane.
40
In osmosis, a _____ concentration of solute means a high concentration of water molecules
A high concentration of solute means a _____ concentration of water molecules.
low, high
41
what are water molecules doing in osmosis
moving from high concentration of water molecules to low concentration of water molecules (meaning for the solute it goes from low to high.)
42
explain how plant cells behave when placed in a solution with a higher concentration of solute.
The water in the cell escapes through osmosis
This is because there is low concentration of water outside the cell meaning the water molecules go from higher concentration to lower concentration.
This is the opposite when the cell is placed in a solution with lower concentration of solute; the water molecules in the solute will enter the cell by osmosis.
43
what surrounds the plant cell that is completely permeable
the cell wall.
44
what happens when water molecules leave the plant cells by osmosis? (when cell is placed in a solution which has low concentration of water molecules)
the cytoplasm shrinks inside the cell. However the whole cell does not shrink as the cell wall still maintains its form.
45
what happens when water enters the cell by osmosis? (in a solution which has high concentration of water)
the plant does not burst as the cell wall provides strength.
46
what is the difference between osmosis and diffusion
osmosis is the net movement of water molecules only. Diffusion is that of particles in general.
47
what are stomata
they are the holes on the surface of the leaf that allow gases into and out of the leaf.
This provides oxygen to respiring cells and carbon dioxide for photosynthesising cells.
It also allows water vapour to evaporate into the atmosphere.
48
how do stomas function
Each stoma is surrounded by two guard cells which control the opening and closing of the cell.
Stomata are usually open during the day and closed at night.
49
water molecules move down/up the water potential gradient
down
50
what is water potential gradient
In simpler terms, it's like water "wanting" to move from where it has more energy to where it has less energy.
definition: Water potential gradient is the difference in energy levels or potential energy of water between two points, influencing the direction and strength of water movement in a system.
51
what is a turgid cell (in plant cells)
it is a cell that is full of water.
52
what is turgor force
The pressure of the water in the cytoplasm in a turgid cell against the cell wall
53
what does turgor force prevent
any more water from entering the cell by osmosis regardless of it environment.
54
what is a flaccid cell (in plant cells)
it is a cell that is dehydrated.
Because of this in plasmolysed cells, the cytoplasm has shrunken. The cell membrane pulls away from the cell wall, leaving a gap between them.
cells which have undergone this are said to be plasmolysed.
55
what are symptoms of a plant with many flaccid cells?
wilting
56
explain plant uptake of water through osmosis
plant roots are surrounded by soil water. root hair cells in the plant have a lower concentration of water than soil water.
water molecules enter these cells through the cell membrane by osmosis.
The root hair cells maximise the concentration of water by actively transporting solutes into the cells
These water molecules slowly permeate other root hair cells ( which have lower concentration) by osmosis.
Osmosis continues as water molecules cross the membranes of deeper root hair cells until they enter the xylem vessels. The water is then transported to the leaves.
57
Explain the effect of osmosis on animal cells.
the effects of osmosis are more dramatic in animal cells as animal cells don't have cell walls like plant cells.
58
what happens if you put an animal cell in a place of higher water concentration?
the water will continue to enter the cell by osmosis until the concentration of the water molecules is higher in the cell.
Enventually, due to the lack of a cell wall, the cell will expand and burst.
59
What happens if you put an animal cell in a place of lower water concentration?
water molecules will exit the cell until the cell becomes crenated
60
what is crenation
crenation describes the formation of abnormal notched surfaces on cells as a result of water loss through osmosis.
61
around 65% of your body mass is ______, another 18% is _______ and 10% is __________ The remainder of your mass is made of nitrogen, sulfur, calcium and iron.
oxygen, carbon, hydrogen
62
what are most of the molecules in living organisms categorised into?
carbohydrates, lipids and proteins
63
what are carbohydrate molecules are made of?
small basic units called simple sugars.
64
what are simple sugars made of?
carbon, hydrogen and oxygen atoms which are sometimes arranged in a ring shaped molecule.
65
what do simple sugars join to make?
polysaccharides such as starch, glycogen and cellulose which are long chains of glucose molecules.
simple sugars can join in pairs to make sucrose.
Glucose and fructose are examples of monosaccharides which are single units of simple sugars.
66
what are proteins?
long chains of amino acids
67
how many types of amino acids are there
20 different types in both animal and plant cells.
68
what are some examples of proteins in plant and animal bodies?
structural proteins in muscle
enzymes that help to control cell reactions.
69
what is a lipid
what we commonly call fat or oil.
70
in room temperature, fats are ______ and oils are ______
solid, liquid
71
What are both fats and oils made of?
fatty acids and glycerol
72
What are lipids important in?
forming cell membranes and many other molecules in the body such as fats in storage cells.
73
what are the basic units of lipids, proteins and carbohydrates?
fatty acids and glucose
amino acids
simple sugars
74
how do you test for starch in a solution?
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.
75
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.
76
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.
77
how do you test for fat?
because fats and oils are insoluble in water, they are dissolved in ethanol.
If fat is present, it will form a cloudy solution.
78
what are enzymes essential for?
they are essential in digestion and breaking down large molecules in food into molecules that are small enough for diffusion through the cells of the gut wall and into our bodies.
79
what is a catalyst
a substance that changes the speed of a reaction, often making it faster.
living cells also use catalysts to change the rate of reactions that happen inside them, known as metabolic reactions.
80
what can enzymes help cause
two or more small molecules to join together, such as when polysaccharides are built from glucose.
larger molecules to break down into smaller ones such as when proteins are broken down into separate amino acids.
81
what is a substrate
a molecule that an enzyme joins with at the start of a reaction.
82
what is the substance that is formed by the end of the reaction called?
a product
83
during a reaction involving enzymes, _____ molecules are changed to ______ molecules.
substrate, product
84
what are enzymes?
proteins
85
what is the shape of an enzyme like?
it is three dimensional and produced by the way the molecule folds up.
86
How are the shapes of substrates and enzymes complementary?
enzymes have a particular space in the molecule which perfectly fits with the substrate molecule.
87
what is an active site in enzymes?
the space in the enzyme into which the substrate fits perfectly.
This is where an enzyme-substrate complex is formed once the substrate fits tightly inside.
This makes it easier for bonds inside the substrate to be rearranged to form products.
once products are formed, they no longer fit the active site and therefore are released.
88
what happens to the substrate molecule when it reacts with the enzyme?
it splits into two product molecules that are released from the enzyme.
89
why do enzymes only work with one certain substrate?
because they are specially formed to do so.
90
what are some examples of enzymes?
amylase- a type of carbohydrase which is found in the mouth, which starts the digestion of starch in food into simple sugars.
protease- digestive enzymes that break down proteins into smaller units.
lipases- digestive enzymes that break down lipids in foods.
91
what are optimum temperatures for enzymes?
temperatures at which enzymes work the best.
92
where are enzymes that work best at 37C found in?
the human body; heart, core of the body,liver, kindney, lungs.
93
what happens to enzymes at lower temperatures than the optimum temperature?
they work slower. (the rate of reaction is slow)
94
what happens to enzymes at higher temperatures than optimum temp?
the structure of the enzyme changes which causes it to not work.
This is a permanent change and when it happens, the enzyme is known as having been denatured.
95
why does the rate of reaction increase as temp increases?
Because at higher temps. there's more kinetic energy in particles so they bump into eachother more ehich increases chances of reaction.
96
what happens when the temp. exceeds the optimum temp?
Because the atoms in the enzyme molecule vibrate faster, it changes the shape of the active site, meaning the substrate won't fit as well. The chances of a reaction occurring decreases.
97
how does an enzyme become denatured?
This happens when the temperature increased so much that the bonds between the atoms in the enzyme start to break, changing the shape of the active site, permanently denaturing the enzyme.
98
What is an optimum pH?
enzymes also work best at a particular pH, called their optimum pH.
99
Different enzymes have different __________ depending on where they are normally found in the body.
optimum pHs
100
How can you investigate the effect of pH on enzymes?
- Set up one tube for each pH to be investigated and add buffer solution (a solution which will keep the contents at a particular pH).
- Add starch solution to each tube then amylase solution.
- Take a sample of each tube every minute or so, then test for starch using iodine solution.
The sample that is the first to stop turning iodine blue-black comes from the tube where the digestion of starch to glucose was the fastest and thus the tube kept at opt. pH
101
Why does pH affect enzymes?
Proteins are made from amino acids joined in a chain which interact with nearby amino acids, forming the 3D shape of an enzyme.
Some of the interactions between the amino acids in the enzyme molecule depend on the pH of the surrounding solvent.
If the pH changes too much from the opt. pH, the shape of the enzyme, especially the active site will change, decreasing chances of a reaction.
102
Plant tissue contains the same types of_______ as animal tissue
chemical molecules (carbohydrates, proteins and lipids)
103
What is a plant?
A producer- Plants produce their own energy, beginning with the process of photosynthesis
104
What happens during photosynthesis?
Plants combine carbon dioxide (from the air) and water (from the soil) to form glucose- a simple sugar and also a carbohydrate.
It transfers energy from light into chemical energy in the bonds of glucose.
The light is absorbed by a green pigment called chlorophyll.
105
What is the byproduct of photosynthesis
Oxygen
106
What happens to the glucose produced by photosynthesis?
Most of it is converted into other substances including starch.
107
What are starch molecules
large carbohydrate molecules made of lots of glucose molecules joined together.
It is insoluble so it can be stored in cells without affecting water movement in and out of cells by osmosis.
108
Where does the energy needed to join simple sugars to make larger carbohydrates come from?
respiration
109
How do you investigate photosynthesis?
We can use an iodine test to show that photosynthesising part of a plant produce starch. Before starting this test, the plant must be left in the dark for 24hrs. This will make sure that the plant uses up its stores of starch (destarching).
110
What is the exact method to investigate photosynthesis?
-Place a destrached plant in light for 1 hour.
-Remove the leaf and place it in boiling water to soften
-Then place the leaf in boiling ethanol heated in a beaker of boiling water.
-This removes the chlorophyll in the leaf so that the results are accurate
-When the leaf has lost its green, place it in a dish and add a few drops of iodine solution.
-The leaf should turn blue/black indicating starch presence.
111
What if following the iodine method, one chooses to investigate the need for carbon dioxide in photosynthesis
-Set up two bell jars on glass sheets
-Sodium or potassium hydroxide reacts with carbon dioxide removing it from the air.
-A dish of the hydroxide is placed in one bell jar
-In the other, carbon dioxide is added by burning a candle.
-Simple destarched plants are placed in each bell jar and the base of the jar is sealed to a glass sheet.
-After a few hours, both leaves are tested and the one in the bell jar filled with CO2 should turn blue-black.
112
How do you investigate the rate of photosynthesis?
-Photosynthesis can be investigated more directly by measuring the amount of oxygen produced by a plant.
- The oxygen is usually collected over water and these investigations are most simply done using aquatic plants.
-Use the glowing splint test on the gas collected to prove the presence for oxygen
-The plant should reignite, showing that the gas was oxygen.
113
