Biology Term 3 & 4 Flashcards
1
Q
Define a Hormone:
A
A chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specified target organs.
2
Q
What are some differences between the Endocrine and Nervous system?
A
Endocrine System - This is the transmission of chemicals i.e. hormones, via the blood. They have slow transmission and the hormones that are carried disperse throughout the body. These have long-term effects e.g. cause long term changes during puberty.
Nervous System - The transmission of electrical impulses via the nerves, The transmission is rapid (up to 100 m/s). The impulse is sent directly to the target organ. These impulses have short-term effects e.g. the movement of a finger.
3
Q
Explain the effects of adrenaline
A
Adrenaline is the fight or flight hormone. It is secreted from the adrenal glands which are located above each kidney. The effects of glucose are as such:
- Heart beats faster, this is to send more glucose and oxygen to the muscles. This creates a thumping heart sensation
- Faster and Deeper Breathing, this is due to increased oxygenation of the blood and removal of CO2. This targets the breathing centre of the brain. This causes panting.
- Vasoconstriction of arterioles in the skin and digestive system, means more blood is available to reach the muscles. This causes the person to go paler and have a dry mouth.
- Vasodilation of skeletal muscle, Processes such as perilstalsis and digestion slow down so that more energy is available for action. This creates the ‘hollow’ tense feeling in the stomach.
- Muscles tense, ready for immediate action. Causes a tense feeling and shivering.
- Liver will convert glycogen to glucose. This means there is more glucose available in the blood to be converted into energy.
- Conversion of fats in the fat deposits into fatty acids. This means there is more fatty acids available in the blood for muscle contraction.
4
Q
Explain the effects of insulin
A
Insulin is made in the pancreas which is both a digestive and endocrine gland. Insulin is produced in the group of cells in the pancreas known as Beta-Islets of of Langerhans. Insulin controls the levels of glucose in the body by the instructing the liver to turn glucose into glycogen when blood sugar levels get too high. Glucose is osmotically active whereas glycogen is not.
5
Q
Explain the effects of testosterone
A
Testosterone is produced by the testes. Testosterone allows the production of sperm as well as with secondary sexual characteristics during puberty such as hair growth.
6
Q
Explain the effects of oestrogen
A
Oestrogen is produced in the ovaries and help with the maturation of the ova. Like testosterone it also helps with the development of secondary sexual characteristics.
7
Q
Define homeostasis
A
It is the maintaining of a constant internal environment.
8
Q
Describe the structure of the skin
A
The top layer of skin is known as the epidermis. On the very bottom of this epidermis is the basal layer in which cells are constantly being divided causing older cells to be pushed to the top. These dividing cells also give rise to the hair. In the basal layer and epidermis there is the black pigment, melanin, which determines the darkness of the skin. Under the epidermis is the dermis which contains sweat glands, blood vessels and nerve endings. Under the dermis there is a layer of adipose tissue or fat deposit used to insulate heat.
9
Q
What happens when the temperature is too low in the body?
A
- Vasoconstriction of blood vessels occur to reduce the amount of heat lost to the surroundings.
- Sweat production stops so less heat is lost through latent heat of vaporisation.
- Shivering - uncontrollable, involuntary bursts of muscle contractions in the limbs. Heat is released as a result of respiration in the muscles.
- Hairs stand up and erector muscles contract. This traps a layer of heat as it has formed an insulating layer.
10
Q
What happens when temperature is too high in the body?
A
Vasodilation of blood vessels - This means that the arterioles widen to allow more warm blood to flow through the blood capillaries near the skin surface. This means heat is lost
Latent Heat of Vaporisation or Sweating - Sweat glands secrete sweat onto the skin surface. When the liquid evaporates it takes heat from the body and cools it down.
11
Q
Why is the regulation of body temperature important?
A
Because all chemical reactions that take place in living cells require enzymes. Any extreme changes in temperature from the usual 37°C can slow down or denature these enzymes. For the same reason the pH levels in the body must also be maintained by homeostasis.
12
Q
Why must the tissue fluid composition be kept steady?
A
Although the cell membrane controls what enters and exits the cell, the tissue fluid supplies and removes these substances when required. If this tissue fluid were to become too concentrated, it would withdraw water from the cells by osmosis. If the tissue fluid was too diluted, the cells would take up too much water from osmosis and become water-logged and swollen.
13
Q
What is the brain’s role in the regulation of temperature?
A
The brain detects any changes from normal by monitoring the temperature of the blood. A region called the hypothalamus contains a thermoregulatory centre in which temperature receptors detect any changes in the blood and co-ordinate a response to them. Thermoreceptors are also found in the skin, which send information about temperature changes to the brain.
14
Q
Describe the regulation of blood sugar levels
A
If sugar levels decrease the Beta-Islets of Langerhans release the hormone glucagon. Glucagon induces the liver to convert glycogen into glucose. If sugar levels increase the islets produce insulin which induce the liver to convert glucose to glycogen.
15
Q
Describe type 1 diabetes, effects and symptoms
A
It is an autoimmune disease in which the Beta-Islets of Langerhans are destroyed by antibodies produced in the immune system. This means that there is a deficiency of insulin in the body.
Symptoms: Swelling of brain which can lead to death, Patient become thirsty, Frequent Urination, and Confusion.
Treatment: Insulin injections, Controlled Diet
16
Q
Explain negative feedback
A
Homeostasis is controlled by negative feedback. Negative feedback is the system of control that causes the body to counteract any deficiencies or surplus of a certain substance in the body. The outgoing impulses counteract the effects that produced the incoming impulses. An example of this is when there is a rise in temperature. This rise triggers responses in the hypothalamus that counteract the rise.
17
Q
Define tropisms
A
Tropisms are growth movements related to directional stimuli. Essentially they are a plant’s response to environmental change. Phototropism is a response in which a plant grows towards or away from the direction from which light is coming. Gravitropism is a response in which a plant organ grows towards or away from gravity. If a plant responds by growing towards the stimuli it is ‘positive’ and if against it is ‘negative’.
18
Q
Advantages of positive phototropism of shoots
A
By growing towards a light source, a shoot brings its leaves into the best situation for photosynthesis. Similarly, flowers are brought into the best position to be seen and pollinated.
19
Q
Advantages of negative gravitropism in shoots
A
These shoots grow vertically. This helps the plant compete for light and CO2. Seed dispersal may also be more effective, and flowers are brought into a better position for insect or wind pollination.
20
Q
Advantages of positive gravitropism in roots
A
By growing towards gravity the roots penetrate the soil which gives the plant better anchorage and a better source of water and minerals.
21
Q
Explain the role of growth substances such as auxin in tropisms
A
Just as humans have hormones for growth rate and extent of growth, plants have growth substances. Unlike hormones, growth substances are found in regions of actively dividing cells such as the tips and roots rather than a specific organ. Auxin is produced in the meristem of the plant. Auxin allows the cells to elongate by causing the cell wall to acidify (The H+ cause H-bonds to break so the cell wall can elongate). Auxin is unevenly distributed according to stimuli e.g. When a shoot is exposed to light the auxin moves towards the shaded side causing the shaded cells to elongate. This causes the shoot to curve as one side of cells are larger than the other.
22
Q
Define inheritance
A
The transmission of genetic information from generation to generation
23
Q
Define chromosome
A
A thread-like structure of DNA, carrying genetic information in the form of genes.
24
Q
Define a gene
A
A gene is a length of DNA that codes for a protein.
25
Define allele
An allele are alternative versions of a gene.
26
Explain the inheritance of sex in humans
Females contain two sex chromosomes called the X chromosome which are of the same size. In males there are two sex chromosomes of different sizes, an X chromosome and a smaller Y chromosome. When gametes are formed they take half the normal number of chromosomes, meaning 23 for humans. All ovum will have their first X chromosome come from the female. However, 50% of sperm have and X chromosome and 50% have a Y chromosome. This means there is equal chance of the offspring being XY or boy or XX or girl.
27
Explain the genetic code and its relevance to forming and ordering amino acids
A nucleotide carries one of the 4 bases, A, T, G, C. A string of nucleotides holds a sequence of these bases. This sequence forms a code which instructs the cell to make particular proteins. Proteins are made of amino acids which will determine the protein based on their type and sequence which are determined by the base sequences. Each group of three bases stand for one amino acid. This means a gene is a sequence of triplets of the four bases, which specifies an entire protein.
28
Explain how proteins are made
A molecule called a messenger RNA or mRNA is used to transfer the information of the codes needed to make proteins to where they are needed in the cell. mRNA is much smaller than DNA and only contains one strand. mRNA also carries a U base instead of a T base which is uracil. Uracil attaches to the DNA base A. To pass on the protein code, the double helix of DNA unwinds to expose the chain of bases. One stand acts as a template. A mRNA molecule is formed along part of this strand, made up of a chain of nucleotides with complementary bases to a section of the DNA strand. The protein-carrying mRNA molecule passes out of the nucleus through a nuclear pore on the membrane. Once in the cytoplasm it attaches itself to a ribosome. The mRNA molecule instructs the ribosome to put together a chain of amino acids in a specific sequence, thus making a protein.
29
Define a haploid nucleus
A nucleus containing a single set of unpaired chromosomes present, e.g. in gametes
30
Define mitosis
Nuclear division giving rise to genetically identical cells.
31
What is the function of mitosis?
1. growth, repair of damaged tissues
2. replacement of cells
3. asexual reproduction
32
Describe the process of mitosis
1. Just before the cell divides, thread-like chromosomes appear in the nucleus.
2. The chromosomes get shorter and thicker
3. Each chromosome replicates itself and makes 2 parallel strands called chromatids.
4. The nuclear membrane disappears and fibres pull the chromatids apart to opposite ends of the cell.
5. A nuclear membrane forms around each set of chromatids and the cell starts to divide. When the nucleus divides into two, one chromatid from each chromosome goes into each daughter nucleus. These chromatids become chromosomes in each nucleus.
6. Cell division is complete giving two 'daughter' cells, each containing the same number of chromosomes as the parent cell.
33
Define meiosis
Nuclear division giving rise to cells that are genetically different.
34
Describe the process of meiosis
1. The chromosomes appear, and just like mitosis the chromosomes shorten and thicken.
2. Homologous chromosomes lie alongside each other .
3. The nuclear membrane disappears and corresponding chromosomes move apart to opposite ends of the cell. This differs from mitosis as in mitosis, it is the chromatids that are pulled apart.
4. The chromosome replicates itself and now consists of two chromatids.
5. A second division takes place to separate the newly formed chromatids.
6. Four gametes are formed, with each containing only half the original number of chromosomes. This creates variation as the maternal and paternal chromosomes meet in different combinations in the zygote.
35
Explain how independent assortment during meiosis produces variation in offspring
When homologous pairs of chromosomes line up during meiosis, they do so randomly i.e. in no particular order. This makes the alleles that end up in a gamete are completely random.
36
Define Genotype
The genetic makeup of an organism in terms of the alleles present
37
Define Phenotype
The observable features of an organism
38
Define Homozygous
Having two identical alleles of a particular gene
39
What is pure breeding?
This is when two identical homozygous individuals breed together to produce the same homozygous alleles.
40
Define heterozygous
Having two different alleles of a particular gene. The offspring of heterozygous individuals cannot be pure bred.
41
Define a dominant allele
An allele that is expressed if present
42
Define a recessive allele
An allele that is only expressed when there are no dominant alleles of the genes present.
43
What is a test cross and how is it performed?
A test cross is a method of determining the genotype of a phenotypically dominant individual (either Heterozygous or Homozygous dominant). To do this ou must:
- Breed the individual with a homozygous recessive individual.
- If after sufficient offspring is produced and no recessive individuals are produced, it is likely that the individual in question is homozygous dominant as they will always pass down the dominant allele.
- If phenotypically recessive individuals are produced as well, then the individual must be heterozygous, as the recessive allele is passed down to the offspring.
44
Explain co-dominance with reference to human blood types
Co-dominance is when two dominant alleles are equally and independently expressed. Heterozygous genotypes will have both phenotypes visible. This is seen in human blood types with type A (IA) and type B (BI) being co-dominant. This means that is a person inherits alleles for both group A and group B they will be blood type AB. However, A and B are both dominant to blood type o (i)
45
Define a sex-linked characteristic
A characteristic which the gene responsible is located on a sex chromosome, which makes it more common in one sex than another.
46
Explain why traits such as haemophilia and colour-blindness are found more commonly in males
This is because males carry the Y chromosome which is shorter than the X chromosome. This means that if an allele is on the Y chromosome it is expressed, even if it is recessive, as they have nothing to cover the allele. This is not the case in females as they require two recessive alleles to express a trait, and only one dominant allele is needed to mask the other. This also means that if a gene is only found on the Y chromosome only males can have that characteristic as females do not posses the Y chromosome.
47
Define Variation
Variation is the differences between individuals of the same species
48
What is the difference between phenotypic and genetic variation?
Genetic variations are those that can be inherited i.e. determined by genes e.g. The many variations in size and coat colour of cats.
Phenotypic variations may be brought about by genes, but are also caused by the environment, or a combination of both genes and the environment e.g. A cat that gets insufficient food will not be the same size as it's litter mates.
49
Define continuous variation
Variation where there is no distinct categories and between the smallest value and the largest value there are infinite intermediates. E.g. Height, Weight, Skin Colour
50
Define discontinuous variation
Variations which take the form of distinct, alternative phenotypes with no intermediates. E.g. Tongue-Rolling, Gender. Discontinous variation is more likely to be expressed by genes alone i.e. they are usually genetic variations and are unlikely to be determined by the environment.
51
Define a mutation
A mutation is a random and spontaneous change in DNA sequence. Mutations are the way new alleles are formed.
52
What is the difference between somatic and germ-line mutations?
A somatic mutation occurs in a single body cell and cannot be inherited. Only cells produced from this mutated cell, by mitosis, will be affected.
A germ-line mutation is a mutation that occurs in the gametes and can be passed onto offspring. With this type of mutation, the whole organism will be affected.
53
Define a gene mutation
A gene mutation is a change in the base sequence in DNA.
54
What is sickle cell anaemia?
Sickle cell anaemia is where a person has defective haemoglobin. When in low oxygen concentrations the distortion and destruction of red blood cells occur. This leads to bouts of sever anaemia. Sickle Cell anaemia occurs due a difference in one amino acid, where valine replaces glutamic acid as a result of faulty replication during meiosis.
55
Why do people who are heterozygous for sickle cell anaemia have a greater chance of survival?
Those who are heterozygous for sickle cell anaemia have virtually no symptoms of anaemia but are more resistant to malaria than the normal, homozygous dominant population. This is because the malaria parasite is unable to invade and reproduce in the sickle cells. Those who are homozygous dominant (HbAHbA) are selected against by malaria and those who are homozygous recessive (HbSHbS) are selected against by sickle cell anaemia. However, those who are heterozygous (HbAHbS) have positive selection due to malaria resistance. This resistance has a great advantage in certain African and South-East Asian countries.
56
Define an adaptive feature
The inherited functional features of an organism that increase its fitness
57
Define fitness
Fitness is the probability of an organism surviving and reproducing in the environment in which it's found.
58
Define transpiration and explain why it is important
The loss of water vapour from the spongy layer of the leaf. Transpiration is important as it provides an upward pulling force to move water and minerals through xylem tissue.
59
How is the rate of transpiration controlled?
By the opening and closing of the leaf stomata. This is because, in an excess of water, the guard cells swell unevenly causing the stomata to open.
60
What are xerophytes?
Xerophytes are plants found in dry conditions that do not have access to a continuous supply of water. They require adaptations that reduce their rate of transpiration. E.g. Marram Grass, Cacti
61
What are adaptations of xerophytes?
- Thick waxy cuticle
- Reduced number of stomata
- Stomata in pits
- Stomata covered in fine hairs
- Leaves reduced to spines
- Long roots
- Enlarged stems to store water
- Reduced rates of photosynthesis
62
Why do xerophytes live in dry areas?
Because they have very little competition and have thus evolved to fill an unoccupied niche.
63
What are hydrophytes?
Aquatic plants that live in environments surrounded by water. They do not need to reduce water loss. E.g Seaweed, Lily Pads
64
What adaptations do hydrophytes have?
- Stomata on top of leaves, so that gas exchange with atmosphere can occur
- Leaves have large surface area, more light can be absorbed. Also helps with flotation.
- Stomata do not open and close, because guard cells are always turgid
65
Why must the rate of transpiration be increased in hydrophytes?
- The rate at which water moves through the plant provides it with support
- Too much water creates issues with cellular processes such as respiration.
- Constant evaporation of water keeps temperature inside the leaf low.
- Water movement assists with removal of waste from cells.
66
What are the requirements for natural selection?
1. Variation within populations
2. Overproduction of offspring
3. Competition for resources
4. Struggle for survival
5. Reproduction by individuals that are better adapted to the environment than others
6. The fittest passing on their alleles to the next generation.
67
Describe selective breeding/ artificial selection
It is the process involving humans selecting individuals with desirable features. These individuals are crossed to produce the next generation. A selection of offspring will show these desirable traits. Any individuals with undesirable traits will be culled.
68
Define evolution
The change in adaptive features of a population over time as a result of natural selection.
69
Define adaptation
The process, resulting from natural selection, by which populations become better suited to their environment over many generations
70
Describe the development of strains of antibiotic resistant bacteria
Antibiotics are drugs used to treat bacterial infections. If a single bacteria contains a drug resistant mutant it can be detrimental due to the rate at which bacteria reproduce. This is very bad when trying to treat bacterial infections and is thus, a threat to humanity. These genes are inherited as per normal and are therefore, inherited by the offspring.
71
Why are bacteria used in biotechnology and genetic engineering?
1. Rapid reproduction rate
2. Their ability to make complex molecules
3. Lack of ethical concerns over their manipulation and growth
4. The presence of plasmids
5. They have DNA and genetic code like all other living organisms.
72
What is the role of the anaerobic respiration of yeast during the production of ethanol for biofuels?
A biofuel is a fuel derived from living matter. The anaerobic respiration of yeast or fermentation produces ethanol. When this ethanol is mixed with petrol it forms bioethanol and can be used in cars.
73
What is the role of yeast in bread-making?
Yeast causes bread to rise as the CO2 from fermentation causes the bread to rise. The ethanol evaporates away as it has a low boiling point at around 78.5°C. To ensure that the dough is airtight it must be kneaded to form sticky gluten . Once O2 runs out the process of anaerobic respiration can begin.
74
Describe the use of pectinase in making juices
Pectinase is used to separate the juices from fruits. Pectinase is harvested from genetically engineered bacteria. The pectinase breaks down the tonoplast. This maximises juice extraction and makes it a lot easier to extract juices from fruits in much larger quantities.
75
Describe the use of lactase in producing lactose-free milk?
When people are lactose-intolerent, the lactose that is found in dairy products such as milk, it is fermented by bacteria, causing symptoms such as flatulence and diarrhea. The immobilised enzyme lactase is used to turn lactose into an Alpha-Glucose and Galactose.
76
Describe the role of penicillium in making penicillin and state how this relates to its industrial manufacturing.
Penicillin is produced in the fungi penicillium as a defense mechanism against the competition for nutrients that bacteria bring to them. Thus, the penicillin produced is used to kill the bacteria. When producing penicillin industrially, the nutrient liquid is seeded with a culture of the appropriate micro-organism, which is allowed to grow for a couple of days. Sterile conditions are essential for this process. As the nutrient supply diminishes, the micro-organisms begin to feel threatened and secrete the antibiotics into the medium. The nutrient fluid containing the antibiotic is filtered off and extracted.
77
Define genetic engineering
Changing the genetic material of an organism by removing, changing or inserting individual genes.
78
What are advantages of using bacteria to produce insulin?
- Using animal insulin is not the same and is therefore, less effective. Insulin made here is identical to human insulin.
- No ethical or religious opposition
- Can produce large quantities.
79
Advantages and disadvantages of inserting genes into crop plants to confer resistance to herbicides
Advantages:
- More yield/ Less competition as herbicides are used to kill surrounding weeds
- Don't have to use as much weed-killer
Disadvantages:
- Remnants of weed killer in food
- Pollen may cross-fertilise closely related weed species
80
Advantages and Disadvantages of inserting genes with pesticide resistance into plants
```
Advantages:
- Kills insects/pests
- This means higher yield
Disadvantages:
- May disrupt ecosystem and could kill useful insects e.g. Bees
- Insects could become immune
```
81
Advantages and Disadvantages of vitamin enhanced crops
```
Advantages:
- Reduction in vitamin deficiencies
Disadvantages:
- Makes products more expensive
- Must buy the seed to grow
```
82
Describe the use of washing powders that use enzymes
Enzymes in biological washing powders are immobilised allowing them to be more easily washed from clothing. They use of enzymes allows stains caused by proteins such as blood to be removed.
83
What is a fermenter?
A large vessel in which the internal environment can be carefully controlled to produce a product from the growth of micro-organisms.
84
Describe batch and continuous fermenting and give advantages for both
Batch Fermenting: When a single fermenter is filled with the micro-organisms and then run for a set period of time.
Advantages: It is a sealed fermenter so there is no
chance of infection
- No accumulation of dead organisms
Continuous Fermenting: When a single fermenter is filled with the micro-organisms which is 'fed' continuously for an indefinite period of time and the products harvested.
Advantages: Economically it is much more efficient
- If maintained the product should be identical
85
What are the different parts of the fermenter?
Impellers: Constantly moves micro-organisms around so that they are in contact with food.
Cooling Jacket: Maintains optimum temperature for micro-organisms to ferment
Sample Line: To test contents
Air in: To let air in for aerobic respiration.
- Steam is used to maintain aseptic conditions as it will kill leftovers from last batch without killing new batch.
86
Describe the process of making insulin
1. Identification of the gene: i) use a radioactive probe, a short piece of DNA that will attach to the gene in the genome. OR ii) Use mRNA in the cell that the gene has been expressed in.
2. Isolation: i) Gene is cut out of genome using restriction enzymes or endonucleases. ii) Reverse transcriptase, converts RNA to DNA. iii) Artificially synthesise piece of DNA in the lab.
3. Insertion into plasmid: Plasmid is cut using restriction enzymes complementary to the sticky ends in the isolated gene. The gene is marked with GFP so we can identify bacteria. The gene bonds with plasmid in a process called splicing. Ligase is used to seal the sugar phosphate backbone. The recombinant plasmid is then inserted back into the bacteria using heat shock. It is now transgenic.
87
Define ecology, ecosystems, biotic, abiotic, population and community
Ecology: The study of organisms
Ecosystems: A defined area in which populations of organisms interact with each other and the environment
Biotic: Living factors
Abiotic: Non-living factors
Population: A group of organisms of the same species in an ecosystem
Community: Groups of populations within an ecosystem.
88
How has agricultural machinery increased food production?
- Machinery replaced animals
- Unlike animals machine don't fatigue and are much faster
- This results in more area farmed per unit time.
89
How have chemical fertilisers increased food production?
```
NPK:
Nitrogen - proteins and enzymes
Phosphorous - for ATP and DNA
Potassium - Balances ion levels
Magnesium - central molecule of chlorophyll
```
90
How have insecticides and herbicides increased food production?
- Insecticides removes pests which consume crops, means greater yield
- Herbicides reduce the plant competition for sunlight water etc. by killing weeds
91
How has selective breeding increased food production?
- Improves yield e.g. larger fruits
- Rate of growth, mature at same time
- Same height (monocrops)
92
State disadvantages for large scale monocultures and intensive live stock production
```
Monocultures:
- Decreases biodiversity
- Deforestation to create monocultures
- Use of excess water disrupts ecosystem
Live Stock Production:
- Pollution of watercourses
- Greenhouse gases from methane
-Deforestation
```
93
Discuss the social, environmental and economic implications of providing sufficient food for an increasing human global population
```
Societal:
- Unequal distribution on a global scale, demand of certain food in certain areas
Environmental:
- Greenhouse gas emmisions
- Deforestation
- Transport and fossil fuels
Economic:
- Transport of food is the greatest source of waste.
```
94
State reasons for famine
- Unequal distribution of food e.g. war, wealth
- Drought: no respiration in roots
- Flooding: Osmosis, salt contamination in roots
- Increasing population
- Poverty
95
State reasons for habitat destruction
- Area for food crop growth and for housing
- Extraction of natural resources
- Marine pollution: oil spills, coral bleaching
96
What impacts do humans have on food chains and webs?
- Removal of a specific producer
| - Removal of a keystone species e.g. Bees
97
State and explain why deforestation is a problem
- Trees remove a lot of CO2 from the air through photosynthesis
- Sometimes trees are burnt producing particulates
- Soil is no longer held in place causing slips and erosion
- Heavy rains will cause flooding as trees are no longer a reservoir.
98
Define a fertiliser. What are organic and inorganic fertilisers?
Fertiliser: Any organic or inorganic material that is added to the soil to supply one or more plant nutrients essential to the growth of the plant.
Organic: Plant or animal broken down by decomposers. It is a slow release fertiliser
Inorganic: Easily dissolved chemicals produced industrially or mined.
99
What are problems with using fertilisers?
- May contain dangerous impurities
- Loss of organic humus layer in the soil and the associated organisms
- Decrease in trace elements within fruits and vegetables
- Leaching of fertilisers into water causes blue baby syndrome and eutrophication.
100
Describe the process of eutrophication
1. increased availability of nitrate and other ions
2. increased growth of producers
3. increased decomposition after death of producers
4. increased aerobic respiration by decomposers
5. reduction in dissolved oxygen
6. death of organisms requiring dissolved oxygen in water
101
What are the effects of non-biodegradable plastics
Direct: Eaten by turtles and fish
- They also get entangled in the plastic
Indirect: Bioaccumulation
102
Describe the process of bioaccumulation
1. Toxin enters food chain and affects non-targeted species
2. These build up as they are ingested by each level in higher concentrations. Different pesticides have different effects on the food chain
103
State the causes, the process and the effect of acid rain
Causes: Sulphur dioxide, Nitrogen Dioxide
Process:
- Gases are released into the atmosphere where they combine with water vapour
- Sulphur dioxide converts to sulphurous acid and finally sulphuric acid.
Effects:
-Direct:
- Certain trees are susceptible e.g. Red Maple
- Soil and watercourses acidify
Indirect: Rain absorbs mineral ions from soil into water course.
104
Describe the greenhouse effect
1. Sun emits short wavelength radiation which warms the Earth
2. Earth loses heat by emitting long-wavelength radiation
3. Greenhouse gases absorb some of the long-wavelength radiation
4. They reradiate this thermal radiation in all directions including back to Earth resultantly warming the atmosphere.
- Without the greenhouse effect Earth would be too cold to support life
105
How does human activity increase amounts of CO2 and methane?
```
CO2:
- Burning fossil fuels for electricity
- Deforestation
Methane:
- Cattle
- Landfill sites. Decay of landfill sites releases methane.
```
106
How is acid rain effects reduced?
- Catalytic converters
- Power Stations remove SO2 pre/post fuel burning
- Low/Non sulphur diesel
107
State and explain effects of climate change
```
Average global temperature increases:
- Polar ice caps melt
- Sea level rises
- Flooding of land results
Extreme Weather events:
- More common and severe e.g. storms
Changes in Rainfall:
- Changes in location, time and frequency of the rain
- Heavy rain damages crops and lack of rain causes drought
Extinction:
- Climate changes rapidly
- Animals and plants cannot adapt quick enough and die out.
```
108
State the negative impacts of female contraceptive hormones in watercourses
- Contraceptive pills are made from synthetic oestregon and progesterone which cannot be broken down in the liver.
- Synthetic hormones are released into watercourses through the urine.
- We eventually ingest this water and it can lower men's sperm count and causes the feminisation of male fish.
109
Define a sustainable resource
One which is produced as rapidly as it is removed from the environment so that it does not run out.
110
What is biodiversity and why must it be maintained?
It is the number of species in an ecosystem. It would be high in a rainforest and low in a monoculture. Biodiversity should be maintained because:
1. We are guardians of the planet for future generations
2. They are a source of medical chemicals
3. Genes for crops
4. Crops (new)
5. Ecotourism
111
What are causes of extinction?
1. Climate Change + Pollution
2. Habitat loss
3. Overharvesting
4. Introduction of alien species: i) Competition for food
ii) Predate - eat iii) Diseases
112
What are the impacts of a decline in population
- Population crash results in a decrease in allele frequency.
- This means certain beneficial alleles may be lost and alleles that are not beneficial to the survival or the organism will result.
113
Give advantages and disadvantages of using zoos to conserve endangered species
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Advantages:
- No predators or hunters
- Supplied with food and water
- Captive breeding programs
- Vets
- Monitoring of mother and young.
Disadvantages:
- Not a natural environment
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114
Give advantages and disadvantages of using National Parks to conserve endangered species
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Advantages:
- Protected from habitat loss and poaching
- Natural Environment
Disadvantages:
- Limited Protection
- Natural loss from predation or death
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115
Give advantages and disadvantages of using Seed Banks over botanical gardens
Advantages:
- Less chance of destruction by pests or natural disasters
- Botanical Gardens need huge amounts of space
Disadvantages:
- Viability of seeds are unknown until grown
116
Describe the process of sewage treatment
1. Screening: Flows through metal grid which removes large solids.
2. Commutation: Coarse solids are grinded and this reduces amount of wastewater solids
3. Grit Chamber: Long, narrow tank designed to slow the flow so that grit settles to the bottom and is removed.
4. Primary clarifier: Removes solids and produces cleaner effluent. Reduces amount of sludge.
5. Aeration Tank: Air pumped into tank encourages microbial growth. Microbes feed on organic material and break them down.
6. Secondary clarifier: Remaining solids are removed by sedimentation. This means effluent is sludge free.
7. Disinfection: Micro-organisms are removed, deactivated or destroyed. Prevents spread of disease.
8. Discharge to surface: effluent returned to environment.
