BIOLOGY module 4 Flashcards
list some abiotic factors
Rainfall
pH
Temperature
Humidity/lack thereof
Presence/level of pollution
Describe areas with low biodiversity
- Few successful number of species
- Stressful/extreme enviroment with few ecological niches
- Relatively few species live in the habitat
- Very specific adaptations to the enviroment
- Simple food webs
- Enviromental change has a major effect on the ecosystem as a whole
- Low biodiversity index (below 0.5)
describe the method of using a poster
- Used to catch small insects
- Insects drawn into the holding chamber via the inlet tube
-Filter before the mouthpiece prevents them being sucked in by the mouth
what are sweep nets used for?
Used to catch insects in areas with long grass.
pitfall traps
- Used to catch small, crawling inverterbrates e.g. beetles, slugs, spiders etc
- Hole dug into ground which insect falls into.
- Must be deep enough so that the insects cant crawl out.
- Trap must be covered so it doesnt fill up with rainwater
point quadrats
- Consists of a frame containing a horizontal bar
- At set intervals long pins are pushed through the ground along the bar
- Each species of plant the pin touches is recorded
frame quadrat
- Square frame divided into equal grids
- Type and number of species within each grid is recorded
How do you collect the most valid and representative sample of ana area with a quadrat?
- Quadrats should be used following arandom sampling technique
- To study how the presence and distribution of organisms across some land varies, quadrats can be placed systematically along belt/ine transect
Three main ways of using frame quadrats
DENSITY - If individual large plants can be seen clearly, count the number of them in a 1m by 1m square quadrat. (density per metre). Gives ABSOLUTE measure.
FREQUENCY - used to study biodiversity in grassland. If each gird represents 1% and there is 1 buttercup in 65/100 grids then the frequency of occurence of buttercups would be 65%.
line transect
Simply a straight line marked across a habitat.
Species that touch the line at regular intervals are identified and recorded.
Results are converted into a drawing that shows the distribution of organisms.
Used to show how communities change along a gradient.
Good way to show the changes qualitatively.
belt transect
Quantitative
Similar to the line transect but gives information on abundance as well as presence/absence of species.
Involves placing quadrats along a line taken through an ecosystem
Short distance - quadrats placed continuously - continuous belt transect
Long distance - quadrats placed at intervals - interrupted belt transect
factors that increase genetic biodiversity
- Mutations in the DNA of the organism, creatign a new allele
- Interbreeding between different populations .This causes alleles to be transferred between the two different populations - GENE FLOW.
factors that decrease biodiversity
Habitat destruction.
Overexploitation.
Hunting.
Agriculture.
Climate change.
human population growth.
genetic bottleneck.
genetic drift.
genetic bottleneck
Few individuals of a population survive disease/environmental change/habitat destruction. Only their allelles are passed on to the successive generation, reducing the gene pool.
genetic drift
the change in frequency of an existing gene variant in the population due to random chance. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation.
polymorphic gene
gene with more then one allele.
monomorphic gene
gene with only one allele
locus
position of gene on chromosome
high proportion of polymorphic gene loci
= high genetic diversity
Why is it advantegeous for a species to have high genetic biodiversity?
likely to have some individuals in the population that carries an advantageous alele which enables them to survive a change of conditions. Without these individuals the species will be extinct.
Factors affect biodiversity
deforestation
Agriculture
Disease
Climate change
How does deforestation affect biodiversity? (4)
- Directly reduces number of trees present in an area.
- If only a specific type of tree is felled then species diversity is reduced.
- Reduces number of animal species in the area (destroys their habitat and source of food)
- Animals may migrate to other areas as a result. this reduces biodiversity of other areas.
How does removing hedgerows affect biodiversity?
- Reduces number of plant species in the area
- Destroys habitat of blackbirds, mice, hedgehogs and many inverterbrates.
How do pesticides and herbicides affect biodiversity?
- reduces animal species by killing pest species. By doing this they also kill food sources of other organisms.
- Herbicides reduce plant diversity by destroying weeds. Also kills food sources for other animals.
How does monoculture affect biodiversity?
- Lowers plant diversity as only one species of plant is present.
- Relatively few animals will be supported by one type of plant, so overall biodiversity decreases.
- Monoculture interferes with nitrogen cycle so contributes to soil depletion.
-Soil depletion produces weaker crops which are more vulnerable to predators, competitiors and disease.
-Farmer will become more dependent on pesticides, herbicides and fertilisers.
How do melting of polar ice caps and rising sea levels affect biodiversity?
- Poles of the earth already have low biodiversity. Could lead to exticntion of the few species living there.
- Species will migrate towards more favourable conditions.
- Rising sea levels reduce habitat diversity be flooding low lying land.
-Saltwater flows further up rivers, reducing habitats of freshwater plants and animals.
How do higher temparatures and less rainfall affect biodiversity?
Non drought resistant species of plants will die out. animals that feed on them will die too.
drought resistant plants (xerophytes) will become more dominant.
animals that used to feed on hydrohphytes will be replaced by animals who feed on xerophytes.
how will the change in insect life cycles and populations affect biodiversity?
Insects adapt to climate change. They act as pollinators. If their lifecycles change, it could affect the lives of many plant species, leading to extinction.
How does disease affect biodiversity?
-Will lower biodiversity initially through bottleneck effect.
- Eventually genetic drift will cause biodiversity to increase. Different genetic populations will occur as a long term result of disease.
Monocultured populations of crops are extremely vulnerable to disease.
