Yr 10 Biology Flashcards
1
Q
Main organelles of plant cells;
A
Nucleus, cell wall, cell membrane, ribosomes, cytoplasm, mitochondria, chloroplasts and vacuole
2
Q
Main organelles of animal cells;
A
Ribosomes, cytoplasm, cell membrane, nucleus and mitochondria
3
Q
relative size of bacterial cells (prokaryotic)
A
0.1-0.5 micrometres (um)
4
Q
Genetic material in eukaryotic cells;
A
Nucleus
5
Q
Genetic material in prokaryotic cells;
A
single DNA loop (+ plasmids in some cases)
6
Q
Function of nucleus;
A
Controls the cell and stores DNA
7
Q
Function of cytoplasm;
A
Where most chemical reactions take place
8
Q
Function of Cell membrane;
A
Controls what enters and leaves the cell
9
Q
Function of mitochondria;
A
Where respiration takes place
10
Q
Function of Ribosomes;
A
Where protein synthesis occurs
11
Q
Function of chloroplasts;
A
Contains chlorophyll which is needed for photosynthesis
12
Q
Function of vacuole;
A
Contains cell sap, stores nutrients
13
Q
Function of cell wall;
A
made of cellulose and strengthens cell + provides rigidity
14
Q
Function of plasmids;
A
Carry genes for replicating DNA
15
Q
Cell differentiation is;
A
Process during which young, immature cells take on individual characteristics and reach their mature form and function (become specialised)
16
Q
Magnification and resolution of electron microscope
A
Magnification - up to 1,000,000X and resolution of <1 nm
17
Q
Magnification and resolution of light microscope
A
Magnification - around 2000X and resolution of 200nm
18
Q
Binary fission;
A
A form of asexual reproduction (mostly in prokaryotic cells) in which an organism divides into two, each part carrying one copy of genetic material
19
Q
Sperm cells adaptions;
A
Heads contain genetic material. They have tails to swim towards the egg cell
20
Q
Nerve cell adaptations;
A
Cells can be very long (up to 2m) to carry messages around the body
21
Q
Muscle cell adaptations;
A
These cells can change their length to help us move
22
Q
Root hair cell adaptations;
A
The root hair gives these cells a bigger surface area to take in water from the soil
23
Q
Xylem adaptations;
A
No top and bottom walls so continuous column of water running through them. Walls are thickened with lignin and support the plant
24
Q
Phloem adaptations;
A
Companion cells provide energy required to transport substances in the phloem
25
What does the nucleus contain?
Chromosomes made of DNA molecules. Each chromosome carries a large number of genes. In body cells the chromosomes are normally found in pairs
26
What is mitosis?
Process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division.
27
Why is cell division by mitosis important?
It plays an important part in the development of embryos, and it is important for the growth and development of our bodies as well. Mitosis produces new cells, and replaces cells that are old, lost or damaged.
28
How can you tell when mitosis has occurred?
Whenever cell division occurs and two identical cells with copies of both chromosomes are formed
29
What is a stem cell?
A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentation
30
What can stem cells from human embryos and adult bone marrow do?
They can be cloned and made to differentiate into many different types of human cells
31
What are some conditions which can be helped by treatment with stem cells?
Diabetes and paralysis
32
What can meristems in plants be used to do?
They can be used to produce clones of plants quickly and economically. Rare species can be cloned to protect from extinction. Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
33
How do substances move in and out of cells across the cell membrane?
Via diffusion
34
What is diffusion?
Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. The difference in the concentrations of the molecules in the two areas is called the concentration gradient.
35
Name 3 Substances transported in and out of cells by diffusion;
Oxygen and carbon dioxide in gas exchange, and the waste product urea from cells into the blood plasma for excretion in the kidney
36
What factors affect the rate of diffusion?
The difference in concentrations, The temperature and the surface area of the membrane
37
Why does a single-celled organism have a relatively large surface area to volume ratio?
To allow sufficient transport of molecules into and out of the cell
38
How are gills in fish adapted for exchanging materials?
Gills have a large surface area, and a good blood supply
39
How are the roots and leaves in plants adapted for exchanging materials?
They are thin which gives a short diffusion distance. They are flat which provides a large surface area to volume ratio.
40
How is the small intestine in mammals adapted for exchanging materials?
Villi - Large surface area to volume ratio, thin walls and good blood supply
41
How are the lungs in mammals adapted for exchanging materials?
Alveoli - good blood supply, thin walls, large surface area and are well ventilated
42
What factors increase the effectiveness of an exchange surface;
Large surface area, thin walls, good blood supply and good air supply
43
What is osmosis?
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
44
What does active transport do?
The substance moves from an area of low concentration to an area of high concentrations, across a partially permeable membrane. This process requires energy produced from cell respiration. (against a concentration gradient).
45
How does the structure of a root hair cell allow active transport?
Root hair cells have a very large surface area due to them being very long and having hair like projections. This allows more active transport of mineral ions to take place so the plant is able to take in as many important mineral ions as possible
46
Describe a use of active transport in plants;
Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth
47
Describe a use of active transport in animals;
It allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration
48
What is organisational hierarchy?
Biological hierarchy refers to the systemic organisation of organisms into levels. Cells make up tissues, tissues make up organs, organs make up organ systems and organ systems make up organisms
49
What is a cell?
Cells are the building blocks of all living organisms
50
What is a tissue?
A group of cells with a similar structure and function
51
What is an organ?
A collection of tissues performing specific functions
52
What is an organism?
An organism is a term for any living thing, an individual living thing that carries on the activities of life by means of organs which have separate functions but are dependent on each other
53
What is an example of an organ system and how does it work?
The digestive system - several organs work together to digest and absorb food
54
What do enzymes work like? And what shape do they have?
A lock and key, and they have a shape that is specific to the substrates they work on. They have a 3-dimensional structure
55
What do enzymes do?
Enzymes are biological catalysts, they help to speed up chemical reactions in the body. They are proteins responsible for various metabolic reactions in our bodies
56
What are the optimum conditions for enzymes?
Different enzymes work best at different pH values. If the temperature gets too high the enzyme will be denatured
57
What does denaturation mean?
Denaturation defines the unfolding or breaking up of a protein, modifying its standard three-dimensional structure.
58
Where is amylase produced and where does it do action?
Amylase is produced in the salivary glands, the pancreas and the small intestine. The enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine
59
Where is protease produced and where does it do action?
Protease is produced in the stomach, the pancreas and the small intestine. The enzymes catalyse the breakdown of proteins into amino acids in the stomach and the small intestine
60
Where is lipase produced and where does it do action?
Lipase is produced in the pancreas and small intestine. These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine
61
What do the digestive enzymes do?
They convert food into small soluble molecules that can be absorbed into the bloodstream
62
What are the products of digestion used to do?
Build new carbohydrates, lipids and proteins. Some glucose is used in respiration
63
Where is bile made and stored and what is its pH and function?
Bile is made in the liver and stored in the gall bladder before being released into the small intestine. Bile neutralises the acid that was added to food in the stomach. It is alkali
64
What conditions increase the rate of fat breakdown by lipase?
The alkaline conditions and large surface area increase the rate of fat breakdown by lipase
65
What is the function of epidermal tissues?
To cover the plant
66
What is the function of palisade mesophyll?
The palisade mesophyll layer is where most of the photosynthesis occurs in the leaf. The palisade cells contain a lot of chloroplasts to help them perform this photosynthesis. The palisade cells are closely packed together to maximize light absorption.
67
What is the function of spongy mesophyll?
The role of the spongy mesophyll is to facilitate the exchange of gases essential to the process of photosynthesis.
68
What is the function of phloem and xylem?
To transport substances around the plant
69
What is the function of meristem tissue?
Meristem tissue is found at the growing tips of shoots and roots. Meristem tissue is important because it allows for plants to grow and repair damaged tissue.
70
How are root hair cells adapted for the efficient uptake of water and mineral ions?
Large S.A. and hairs all over
71
What is the role of stomata and guard cells?
To control gas exchange and water loss
72
What does the xylem do?
It transports water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes strengthened with lignin adapted for the transport of water in the transpiration stream
73
What does the phloem do?
Transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. Phloem is composed of tubes of elongated cells
74
What is translocation?
the movement of food molecules (dissolved sugars + amino acids) through phloem tissues
75
What factors affect the rate of transpiration?
Changing temperature, humidity, air movement and light intensity
76
Photosynthesis word equation;
Carbon dioxide + water + light energy ==> glucose + oxygen + ENERGY
76
What is the transpiration stream?
It is the movement of water through a plant, from the roots to the leaves, via the xylem vessels
77
Balanced symbol equation for photosynthesis;
6CO2 + 6H20 + light energy ===> C6H12O6 + 6O2
78
Where does the energy for photosynthesis come from?
Cells use carbon dioxide and energy from the Sun
79
What factors affect the rate of photosynthesis?
Shortage of light, low temperature and shortage of carbon dioxide
80
What are limiting factors?
A limiting factor is a variable of a system that causes a noticeable change in output or another measure of a type of system.
81
What is inverse proportion?
If one variable decreases, the other decreases in the same proportion.
82
What is the inverse square law and light intensity?
the light intensity is inversely proportional to the square of the distance (light intensity ⍺ 1/distance² )
83
What are the six uses of glucose by plants?
Used for respiration, converted into insoluble starch for storage, used to produce fat or oil for storage, used to produce cellulose - which strengthens the cell wall, used to produce amino acids for protein synthesis and used to produce proteins
84
How do plants use nitrate ions that are absorbed from the soil?
Plants use nitrates as a supply of nitrogen, which is needed to make proteins for healthy growth.
85
What is transpiration?
The loss of water from leaves by evaporation through the stoma
86
Why is transpiration important?
Useful for cooling the plant
mineral transport
getting water to cells
87
Approximate size of an animal cell;
10-30 um
88
Approximate size of a plant cell;
up to 100um
89
Why do muscle cells contain many mitochondria?
they require a large amount of energy to function - more than other cells
90
What does the acrosome of the sperm cell contain?
Contains enzymes that help to penetrate the egg's coats.
91
What is the equation for magnification?
Magnification = image size/object size
92
How does the timing of cell differentiation differ between plants and animals?
Plant cells take longer to differentiate
93
How are neurons are specialised for their function?
Specialised projections - axons allow neurons to transmit electrical + chemical signals
Cell body (soma) contains genetic information
Dendrites allow them to receive thousands of signals to other cells
94
2 advantages of a light microscope over electron microscopes;
They can be used to observe live and dead cells, easier to use, cheaper
95
What has the magnification of electron microscopes allowed scientists to do that wasn't possible with light microscopes?
View the organelles within a cell
96
Why must electron microscopes be kept at specific temperatures, pressures and humidity levels?
Moisture forms on cold surfaces as temperature drops below the dew point, moisture can cause a failure in the electronics and can affect image quality. Gas molecules scatter electron beams, so the vast majority of studies involving electron microscopy have to be at very low pressures
97
What is resolution?
The ability of a microscope to distinguish details of a specimen or sample - clarity of an image produced by a lens
98
What kind of image quality is a microscope with high resolving power able to produce?
The higher the resolving power, the smaller the details of the image quality
99
What is the structure of chromosomes?
Each chromosome has two short arms and two long arms. These arms are held together at the center by the centromere.
100
What is a gene code for?
Genetic code refers to the instructions contained in a gene that tells a cell how to make a specific protein
101
Describe two ways humans use stem cells from plant meristems;
to make new cells and tissues (including blood cells) and to grow new organs for transplantation
102
What is the first stage of the Cell Cycle?
Interphase; the cell grows, organelles (such as ribosomes and mitochondria) grow and increase in number, the synthesis of protein occurs, DNA is replicated (forming the characteristic 'X' shape) and energy stores increase.
103
What is stage 2 of the cell cycle?
Mitosis
104
What is stage 3 of the cell cycle?
Cytokinesis - two identical daughter cells form when the cytoplasm, and cell membrane divides
105
What is therapeutic cloning?
Involves producing an embryo by cloning a body cell taken from a patient. Stem cells taken from this embryo can be used in medical treatments
106
Advantages of therapeutic cloning;
Embryo produced could be harvested to obtain the embryonic stem cells
Would not be rejected as they would have the exact same genetic make-up as the individual
107
Disadvantages of therapeutic cloning;
Is it right to create embryo's only to destroy them?
Embryo's could come to be viewed as a commodity as opposed to something that could develop into a human
At what stage of development should an embryo be considered a person?
108
How does a steep conc. gradient increase diffusion?
The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse
109
How does a large SA increase diffusion?
More space for molecules to diffuse across the membrane
110
How does temperature increase diffusion?
The higher the temperature, the more kinetic energy the particles have so they will move faster and will mix faster
111
As organisms increase in size, their surface area to volume ratio.......?
Decreases
112
why do larger multicellular organisms need specially adapted transport systems?
because simple diffusion would be too slow to transport nutrients and remove waste
113
How does bile speed up the breakdown of fat into glycerol and fatty acids by lipases?
emulsifies fats, SA to vol ratio increases, increasing the rate of reaction as more of the lipid can be broken down by the enzyme
114
What can a potometer be used for?
To measure the rate of transpiration
115
Why is translocation important?
Supplies energy to where its needed for respiration
food prepared by the leaves can reach other parts of the plant
116
Adaptation of phloem cells;
Sieve tubes have perforated ends, so their cytoplasm connects one cell to another. Sieve tubes translocate sugars and amino acids within their cytoplasm.
117
How does magnesium deficiency decrease photosynthetic rate?
through light reaction and CO2 assimilation
118
What does the waxy cuticle do?
acts as a barrier to stop water evaporating from the cells
119
Food test for starch;
Iodine - orange to blue/black
120
Food test for proteins;
biuret - starts blue turns purple
121
Food test for sugar;
Benedict's - MUST BE HEATED FIRST starts blue turns green/yellow if the amount is low, orange/brick red if it is high
122
Food tests for lipids;
Ethanol - clear goes to cloudy/ milky
123
Prefixes and what they should be multiplied by;
Centi - 0.01
milli - 0.001
micro - 0.000001
nano - 0.000000001
124
What is flaccid?
When all the water leaves the cell and the solution is more concentrated out of the cell. Therefore it is a hypertonic solution.
125
What is turgid?
When water has moved into a cell and therefore it is a hypotonic solution.
126
What has happened when a cell has become flaccid?
The cell has been put in a hypertonic solution and has become plasmolysed because all the water has moved out of the cell and the cell membrane has pulled itself away from the wall because the cytoplasm has shrunk.
127
What is metaphase?
When the chromosomes line up on the equator of the cell and attach their spindle fibres with their centromeres
