BIOLOGY PART 1 and 2 Flashcards
(216 cards)
1
Q
Animal cells contain
A
Nucleus Cell membrane Cytoplasm Mitochondria Ribosomes
2
Q
Plant cells contain
A
Nucleus Cell membrane Cytoplasm Mitochondria Ribosomes Cell wall Chloroplasts Vacuole
3
Q
Nucleus
A
Contains DNA and controls cell activity, and instructions for making new cells/organisms
4
Q
Cell membrane
A
Controls what goes in and out of the cell
5
Q
Cytoplasm
A
Liquid gel in which chemical reactions take place e.g. Respiration
6
Q
Mitochondria
A
Structures in the cytoplasm where energy is produced during respiration
7
Q
Ribosomes
A
Where protein synthesis takes place (making proteins from amino acids)
8
Q
Cell wall
A
Made from cellulose to strengthen and supports the cell
9
Q
Chloroplasts
A
Found in green parts of plants. Contains chlorophyll which absorbs light energy to make food by photosynthesis
10
Q
Bacterial cells contain
A
Cytoplasm Cell membrane Cell wall Loop of DNA Capsule
11
Q
Loop of DNA
A
Controls the cell, as bacterial cells do not have a nucleus
12
Q
Capsule
A
Slimy capsule around outside of cell wall to protect it from antibiotics
13
Q
Fungal cells are … than bacterial cells
A
Larger, and can be seen using a light microscope
14
Q
A fungal cell wall is made of
A
Chitin
15
Q
Why were bacterial cells discovered later?
A
Not enough advanced technology
Bacterial cells are much smaller
16
Q
Yeast cells are a
A
Single celled organism
17
Q
Yeast cells contain
A
Nucleus Cytoplasm Cell membrane Ribosomes Mitochondria Cell wall
18
Q
Palisade cell (from a leaf)
A
Absorbs light for photosynthesis
Contains chloroplasts which contain the pigment chlorophyll
19
Q
Muscle cell
A
Contracts to provide movement
Contains mitochondria which provides the energy for contraction
20
Q
Root hair cell
A
Absorbs water and mineral salts from soil
Hair like structure to increase surface area to absorb more water/minerals
21
Q
Sperm cell
A
Fertilises female gamete
Tail to swim
Mid section is full of mitochondria for energy to swim
22
Q
Red blood cell
A
Absorbs oxygen and transports it around the body
No nucleus - more haemoglobin can be packed in, more space to carry oxygen
Biconave shape so it’s flexible and fits through small capillaries
23
Q
Ciliated cell (in oviduct)
A
Moves egg near uterus
Cilia on surface - beats regularly so egg moves down oviduct
Contains mitochondria for energy so cilia can move
24
Q
Nerve cell (motor neurone)
A
Transmits nerve impulses
Contains fibres (dendrites) that connect to other neurones
Axon surrounded by myelin sheath to insulate and speed up transmission of nerve impulse
25
Diffusion
Movement of particles from a high area of concentration to a low area of concentration. No energy required
26
The greater the difference in concentration, the ... the rate of diffusion
Faster
27
Diffusion occurs in
Gases and liquids
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Why can diffusion not occur in solids?
Particles are not free to move
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Large surface area ... the rate of diffusion
Increases, more area is exposed so more diffusion can take place
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Higher temperature ... the rate of diffusion
Increases, the hotter it is the more kinetic energy for diffusion
31
The stomach is an organ that contains
Muscular tissue
Glandular tissue
Epithelial tissue
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Muscular tissue
Contracts for movement
| Churn up contents
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Glandular tissue
```
Produces hormones and enzymes
Produce digestive juices
Layer of cells
Make chemicals e.g. Acid
Lines inside of organs
Creates thick mucus to coat cells
```
34
Epithelial tissue
```
Cover outside and inside of stomach
Arranged evenly
Smooth allowing organs to easily move
Layers of cells
Protective coat around the organ
```
35
Tissues
Groups of similar cells that work to carry out a particular function
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Organs
Groups of different tissues that work to perform a certain function
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Organ systems
Group of organs working together to perform a function, organ systems form organisms
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Digestive system - Salivary glands
Produces the enzyme amylase in saliva
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Digestive system - Liver
Bile is produced
- neutralises stomach acid
- emulsified fats
40
Digestive system - Gall bladder
Where bile is stored before released into small intestine
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Digestive system - Large intestine
Where excess water is absorbed from undigested foods, producing faeces
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Digestive system - Small intestine
Where digested foods are absorbed and move into the blood
| Produces amylase, lipase and protease to complete digestion
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Digestive system - Rectum
Where faeces are stored, before leaving through the anus
44
Digestive system - Pancreas
Produces protease, amylase and lipase and releases them into the small intestine
45
Digestive system - Stomach
```
Pummels food with its muscular wall
Produces protease, amylase and lipase
Produces hydrochloric acid
- to kill bacteria
- give correct pH for protease enzymes to work (pH2 - acidic)
```
46
How are cone cells in the eye adapted to carry out its function?
- Outer segment of cell has a chemical called visual pigment - chemically changes in colour to allow you to see in colour
- The centre has lots of mitochondria, releases energy allowing visual pigment to reform
- Specialised nerve cell that transmits signals to brain so colour is continuously seen
47
How are fat cells adapted?
- small cytoplasm to allow space for fat to be stored
- few mitochondria as they do not use much energy
- can grow to 1000 times its original size
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Tissues - examples?
Epithelial
Muscle
Blood
Bone
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Organs - examples?
```
Stomach
Heart
Kidney
Lung
Skin
Small intestine
```
50
Organ systems - examples?
```
Brain
Circulatory
Digestive
Glandular
Nervous
Skeletal
```
51
Pancreas and salivary glands make digestive juices that
Lubricate food
| Carry enzymes to aid digestion
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Digestion
Breakdown of large food molecules into smaller particles that can pass through the gut wall and be absorbed into the blood
53
Absorption
Process by which smaller food particles are taken into the blood. They pass through the gut-wall into the blood from the gut environment
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Plant organs contain
Stem
Roots
Leaves
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Organ: stem
Supports the plant
| Transports substances through the plant
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Organ: leaf
Produces food by photosynthesis
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Organ: roots
Anchors the plant
| Takes in water/minerals from the soil
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Leaf - upper epidermal tissue
Thin and transparent
Waxy cuticle
Allows light to pass to the mesophyll to protect the leaf and stop water loss
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Leaf - palisade mesophyll
Regular shaped cells
Near upper surface
(Where most chloroplasts are found)
Absorbs the maximum amount of sunlight
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Leaf - spongy mesophyll
Irregular shaped cells
Air spaces
Increases surface area for CO2 absorption to maximise
Allows gases to diffuse
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Leaf - lower epidermal tissue
Surrounded by guard cells
Allows gases to diffuse
Guard cells open/close stomata
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Leaf: vascular bundles
Contains xylem and phloem tubes
| Transport substances from roots to the shoots and leaves
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Leaf - guard cells
Opens and closes stoma to allow gas exchange
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Why do plants need glucose?
- used in respiration to release energy
- joined together to make starch for storage
- combined with nutrients to make proteins for growth
- joined to make cellulose for cell walls
- converted to fats and oils for the seeds
- converted to fructose for the fruit
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Photosynthesis equation
Carbon dioxide + water -> (light energy) -> oxygen + glucose
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Limiting factors - photosynthesis
Light intensity
CO2
Temperature
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What happens during photosynthesis?
Light energy is absorbed by chlorophyll (in chloroplasts)
The energy is used during by converting CO2 from the air and water from the soil into sugar (glucose)
Oxygen is a by product
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Photosynthesis - light intensity
A shortage of light means less energy to power the reaction
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Photosynthesis - temperature
A low temperature limits the rate of photosynthesis as molecules move slower so there are less reactions, however too high will cause enzymes to be denatured (40 degrees roughly)
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Photosynthesis - CO2 concentration
This will limit the rate as there are less molecules in the reaction. A levelled off line on the graph shows it has reached its optimum point.
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How can you grow plants in the ideal environment?
Grow then in a greenhouse as limiting factors can be controlled
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Uses of glucose (from photosynthesis) in plants and algae
Converted into insoluble starch for storage
| Used in respiration
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Physical factors affecting organisms
```
Temperature
Availability of nutrients
Availability of light
Availability of water
Availability of oxygen
Availability of CO2
```
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How temperature affects organisms
Affects the rate of an organisms metabolism
Some cannot tolerate extreme temperatures
Organisms with a high temperature may also struggle to tolerate extreme conditions
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How availability of nutrients affects organisms
Nutrients e.g. Nitrate are essential for growth of plants/microorganisms
A low concentration would cause organisms to struggle to grow and survive
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How availability of light affects an organism
Required as an energy source for photosynthesis
| In low light intensities, plants grow very slowly
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How availability of water affects organisms
All organisms require water
Chemical reactions take place in water solutions
An absence of water causes cells and in turn, organisms to die
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How availability of oxygen affects organisms
Essential for aerobic respiration
May become limited in soil - so roots cannot grow and absorb the minerals/water
May become limited in water, so aquatic organisms struggle to respire
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How availability of CO2 affects organisms
Essential for photosynthesis
| Limited where there are many plants - reducing rate of growth
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Water and CO2 are used to ... food during respiration
Synthesise
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Phosphate - plants
For growth and respiration
Component of DNA
Deficiency symptom - discoloured leaf and poor growth
82
Magnesium - plants
Makes chlorophyll green
| Deficiency symptom - chlorophyll goes yellow
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Nitrate - plants
Found in water, creates amino acids which create proteins
| Lack of nitrate - stunted growth
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Potassium - plants
For photosynthesis and respiration
Must be present for respiration enzymes to work
Deficiency symptom - discoloured leaves and poor growth
85
Transect
A line across a habitat/ part of a habitat
| The number of organisms of each species can be observed and recorded at regular intervals along the transect
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Quadrat
Organisms underneath, usually plants, can be identified and counted
87
Why should quadrats be randomly placed?
So a representative sample is taken
| The validity and reproducibility of the results increases as the results from more quadrats are analysed
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Proteins
Made up of long chains of amino acids
| Fold into a specific shape which dictates its function, another molecule will then fit into it
89
Uses of proteins in the body
```
Keratin in the hair/skin
Channels in cell membrane
Hormones
Haemogoblin in red blood cells
Antibodies
Collagen in blood vessel walls, skin, tendon and bones
Fibrin in blood clots (scabs)
Elastin in lungs/blood vessel walls
```
90
Catalysts
Substances that speed up reactions without being changed or used up
91
Biological catalysts
```
Enzymes, enzymes are proteins
Found in long chains
Speed up reactions
Specific (only catalyse a particular reaction)
Re-used
```
92
All proteins contain the elements
```
Carbon
Oxygen
Nitrogen
Hydrogen
Some sulphur
```
93
Reactions sped up by catalysts
Proteins
Respiration
Proteinsynthesis
94
You can change the shape of a protein by
Heating it
Changing its pH
Reacting it with chemicals e.g ethanol
95
What happens if a proteins shape changes?
It will not be able to carry out its function
| It will be denatured
96
How does pH affect the active sight?
It effects the forces that hold the enzyme molecule together
97
What factors affect enzymes
pH
| Temperature
98
Active sight
A specific shape that only a certain type of reactant (substrate) will fit into
99
How do enzymes affect activation energy?
It lowers the activation energy, so reactions occur at a greater rate
Particles do not need to collide with as much energy
100
How does temperate affect the rate of reaction with enzymes?
If it is too low, the rate of reaction falls as there is less kinetic energy
If it is higher, particles collide with more energy so the rate of reaction increases
If it is too high, the enzyme denatures and the active sight shape changes so the substrate can no longer bond. The rate of reaction falls
101
Digestive enzymes
Break down big molecules into smaller ones
102
Big molecules (digestion - examples)
Starch
Proteins
Fats
103
Small molecules (digestion - examples)
Sugars
Amino acids
Glycerol
Fatty acids
104
3 enzymes - digestive system
Amylase
Protease
Lipase
105
Amylase
Concerts starch into maltose and other sugars
106
Protease
Converts protein into amino acids
107
Lipase
Converts lipids into glycerol and fatty acids
108
Where is amylase made?
Salivary glands
Pancreas
Small intestine
109
Where is protease made?
Stomach (pepsin)
Pancreas
Small intestine
110
Where is lipase made in?
Pancreas
| Small intestine
111
How does bile emulsify fats?
Breaks fats into tiny droplets
| There is then a larger surface area of fat for lipase to work with so digestion is quicker
112
How does bile neutralise acid in the stomach?
The hydrochloric acid in the stomach makes the pH too acidic for enzymes to work
Bile is alkaline so it neutralises the acid
113
Where is bile stored and released into?
Stored in the call bladder
| Released into small intestine
114
Biological washing powders
Contain enzymes (protease/lipase) to break down fats and proteins in stains
115
Enzymes must work well in solutions with a high pH because washing powders are
Highly alkaline
116
What is the range of temperatures enzymes must work at
10-90 degrees
117
When can enzymes be used in home and industry?
If microorganisms produce enzymes that pass out of the cells
118
Biological detergents are more effective at ... temperatures
Lower
119
Advantages of biological washing powders
Enzymes work at low temperature saving energy
More efficient at removing stains
Help delicate fabrics get cleaned without damaging then by a hot wash
120
Disadvantages of biological detergents
May lead to allergies and irritation
| If clothes are not rinsed, the enzymes may remain in the clothing which would digest protein in the skin
121
Enzymes used in industry
Biological washing powders
'Pre-digested' baby foods
Diet foods/slimming products
Fruit juice
122
How does the function of enzymes affect confectionary/slimming products?
Breaks cheap starch into glucose
| This changes to fructose syrup (by isomerase) so less of it if needs to get a sweeter taste
123
How does the function of enzymes affect baby food?
Protease 'pre-digests' the proteins so it is easier for the babies to eat and absorb into their blood
124
How does the function of enzymes affect fruit juice?
It makes it sweeter
125
How does the function of enzymes affect meat?
It tenderises and makes it softer
126
Properties of industrial enzymes
Long shelf life
Withstand high temperatures
Can work in the presence if chemicals that would otherwise stop enzymes working
127
Enzymes in the home
Used to break down food stains as biological detergents
128
Advantage of enzymes
Enzymes lower the temperatures and pressures often needed for chemical reactions
They are specific
Biodegradable
129
Disadvantages of enzymes
Sensitive to surroundings (changing pH or temperature may stop them working)
Expensive to control the conditions
130
Respiration
The process of releasing energy from glucose, which goes on in every cell
131
Aerobic respiration
glucose + oxygen -> carbon dioxide + water + energy
132
Aerobic respiration is respiration using...
Oxygen
133
Aerobic respiration occurs inside...
Mitochondria
134
The energy respiration releases is used to...
- Build larger molecules from smaller ones (proteins from amino acids)
- Allow muscles to contact in animals
- Allow birds/mammals to maintain a constant body temperature
- In plants to build up sugars, nitrates and nutrients into amino acids which are built into proteins
135
Cyanide
A toxin that stops respiration by stopping enzymes involved in the process from working
136
How can exercise affect us?
The depth and rate of breathing increases
Heart rate increases
Increases supply of blood flow to muscles of sugar/oxygen
Removal of CO2 increases
137
How is glycogen used during exercise?
Glucose from food can be stored as glycogen
Mainly stored in the liver but each muscle has its own store
During vigorous exercise, glucose can be converted back to glucose to provide further energy
138
Anaerobic respiration
Glucose -> lactic acid + (some) energy
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Anaerobic respiration is respiration without
Oxygen
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What is anaerobic respiration?
The incomplete breakdown of glucose into lactic acid. It does not release as much energy as aerobic respiration but is useful in emergencies
141
Lactic acid - anaerobic respiration
Lactic acids builds up in muscles, which is painful.
| It tires out muscles- they stop contacting efficiently
142
What is oxidation?
Blood flows through the muscles to removed the lactic acid by oxidising it to CO2 and water
143
Every cell contains ... pairs of chromosomes
23
144
What is a gene?
A section of DNA
145
What is a chromosome?
Made up of DNA
146
What is a diploid number?
A full set (23 pairs of chromosomes)
147
Sex cells only have ... single chromosomes
23
148
What is mitosis?
Mitosis is when a cell reproduces itself by splitting to form two identical offspring
149
Mitosis makes new cells for...
Growth
Repair damaged tissue
Replace worn out tissue
150
DNA fingerprinting is used for...
Forensic science
| Paternity testing
151
What do genes do?
They code for a specific protein
| They tell cells the order for the amino acids
152
What is the exception to everyone having unique DNA?
Identical twins
| Clones
153
Before cells divide in mitosis, what must happen?
The DNA must make a copy of itself
154
How does DNA make a copy of itself?
DNA is double stranded
The molecule unzips
This exposes DNA based
These bases then join to spare, complimentary bases
The bases then match to create an exact copy
155
Which DNA bases join together?
A - T
T - A
C - G
G - C
156
Mitosis is ... reproduction
Asexual, so there is no variation
157
How does the cell create an exact copy of itself in mitosis?
DNA replicates
The two duplicated chromosomes like up in the centre of the cell
Spindle fibres form
Each chromosome splits into two identical copies
Each copy moves to opposite ends of the cell
A membrane forms around each set
This becomes the nuclei
The cytoplasm then divides leaving two new cells that are identical
158
Meiosis
Produces cells which have half the number of chromosomes (gametes)
159
Where does meiosis occur and what does it result in?
It happens in sex organs and results in variation
160
Before meiosis occurs what should happen?
Before the cell divides, it duplicates its DNA
161
How does a cell create gametes through meiosis?
In the first division, chromosome pairs line up in the centre
The pair gets pulled into two separate cells as they are attracted to opposite poles (each cell has one copy of each chromosome)
In the second division, they line up again in the centre and split
You are left with four gametes each with a single set of chromosomes
162
Why does meiosis occur?
For sexual reproduction
163
What happens to gametes during fertilisation?
A single body cell with new pairs of chromosomes are formed
| This cell then divides repeatedly by mitosis to develop into a new individual
164
What are stem cells?
Embryonic stem cells can turn into any type of cell
165
Where can stem cells be found?
Adult bone marrow
| Human embryos
166
What is differentiation?
The process by which a cell changes to become specialised for its job
167
Are stem cells undifferentiated?
Yes
168
How can stem cells be used?
Nerve cells- helping those paralysed by spinal cord injuries
Beating heart muscle cells- those with heart disease
Insulin producing cells- those with diabetes
169
Arguments for stem cells
- those who are alive are more important than an embryo
- unwanted embryos from fertility clinics could be used instead
- medicine uses them to cure disease
- could replace faulty cells
170
Arguments against stem cells
- each embryo is a potential human life
| - scientists should find other ways to obtain stem cells rather than using them from embryos
171
In asexual reproduction, the offspring contain the ... alleles as the parent
Same (they are genetically identical)
172
Why does variation occur in sexual reproduction?
When the gametes fuse, one of each pair comes from the parents
173
What determine the sex of the offspring?
One of the 23 pairs of chromosomes is different, and carries the gene that determines sex
174
Which chromosomes determine male characteristics?
All men have an X and a Y chromosome
| The Y chromosomes causes the male characteristics
175
What chromosome determines the female characteristics?
All women have to X chromosomes
| The combination of XX is what allows female characteristics to develop
176
What is an allele?
An allele is a version of a gene
| E.g. The gene could be Hh and the alleles would be H and h
177
What is a dominant allele?
It controls the development of a characteristic when it is present in only one of the chromosomes
178
What is a recessive allele?
It controls the development of characteristics only if the dominant allele is not present
179
What is a genotype?
What alleles you have
180
What is a phenotype?
The characteristic displayed by the genotype
181
What is a heterozygous?
2 different alleles
182
What is a homozygous?
2 of the same alleles
183
Who worked out the main principles of inheritance?
Gregor Mendel
184
What 3 conclusions did Mendel reach?
- Characteristics in plants are determined by "hereditary units"
- Hereditary units are passed on from both parents (one unit from each parent)
- Hereditary units can be dominant or recessive - if an individual has both, the dominant characteristic will he expressed
185
What are hereditary units?
Genes
186
Why were Mendel's discoveries not recognised until after his death?
He published his work in an obscure journal
DNA, chromosomes and genes were not discovered yet
People couldn't accept the link between plants and animals
He was a monk, so wasn't as respected
187
What does DNA stand for?
Deoxyribose Nucleic Acid
188
How do genes control characteristics?
DNA forms a helix that protects it
Phosphate backbone
Bases
189
Why do the bases match together?
The shape of the molecule allows them to fit together
190
Chromosomes have ... folded DNA
Tightly
191
What are the four bases called?
Cytosine & Guanine
| Adenine & Thymine
192
What is a triplet code?
Three bases joined with the opposite base
193
One triplet code creates an...
Amino acid
194
A chain of amino acids make a...
Protein
195
What forms the bond between bases?
A hydrogen bond
196
What is cystic fibrosis?
Genetic disorder of cell membranes
| Body produces sticky mucus in air passages/ pancreas
197
Cystic fibrosis - explain the alleles
The allele that causes the disease is recessive 'f'
People with only one 'f' will not have the disorder (carriers)
To get the disorder, both parents must be carriers or sufferers
E.g. 1 in 4 chance if parents are both carriers
Only a sufferer if you have two 'f' alleles
198
What is Polydactyly?
Genetic disorder where baby's are born with extra fingers/toes
Not life threatening, little side effects
199
Polydactyly - explain the alleles?
Caused by the dominant allele 'D'
Can be inherited if one parent carries the defective allele
The parent with that allele will also suffer as the allele is dominant
E.g. 50% chance of child having disorder if one parents has the 'D' allele
200
What is embryo screening?
The screening of embryos to search if their alleles may cause a genetic disease m
201
Arguments for embryo screening
Stops people suffering
There are laws to stop it going too far
During IVF most embryos are destroyed anyways, this just allows the selected one to be healthy
Treating disorders is expensive
202
Arguments against embryo screening
People may use screening to pick their most desirable baby
Rejected embryos were potential human life
Screening is expensive
Implies those with disorders are 'undesirable' which increases prejudice
203
What is speciation?
The development of a new species
204
What 2 things lead to speciation?
Isolation
| Natural selection
205
What is a species?
A group of similar organisms that reproduce to give birth the fertile offspring
206
Why does speciation occur?
When populations of the same species become so different they can no longer breed to produce fertile offspring
207
What is isolation?
When a population is levies is separated
208
What are the 4 stages of speciation?
Isolation - 2 species become separated
Genetic variation - they show variation because of the range of alleles
Natural selection - pass on characteristics to next generations
Speciation - populations become so different that interbreeding is no longer successful
209
Extinction happens if you can't ... quickly enough
Evolve
210
Reasons species become extinct
- new predators
- more competition
- catastrophic event e.g volcano
- diseases
- new species develops (speciation)
- change in environment
211
What are fossils?
The remains of plants and animals
212
3 ways fossils form in rock
- Gradual replacement by minerals (most common)
- Casts and impressions
- Preservation in places where no decay occurs
213
How does gradual replacement by minerals cause fossils to form?
Thing like bones do not decay easily
They get replaced by minerals as they decay and form a rock like substance shaped like the original bone/shells/teeth etc.
The surrounding sediment turns to rock but the fossil stays distinct in the rock
214
How do casts and impressions lead to fossils?
Fossils can form if the organism is buried in a soft material like clay
The clay hardens and the organism decays leaving a cast
E.g a plants roots can be preserved as casts
Things like footprints leave impressions in soft materials
215
How does preservation lead to fossils forming?
-In tar pits/ amber (clear yellow stone made from fossilised resin) there's no oxygen or moisture
Therefore decay microbes cannot survive
-In glaciers it's too cold for decay microbes to work
-Peat bogs are too acidic for decay microbes
216
Why can we not be sure on how life began?
Lack of valid and reliable evidence
This is because it's believed early organisms were soft bodied and decayed completely
Therefore the fossil record is incomplete
Geological activity may have destroyed fossils e.g tectonic plates moving
