Unit 3 Flashcards
Definition of food security
the ability of a human population to access food of sufficient quality and quantity
Natural factors which affect food production (5)
drought, pests, flooding, disease, desertification
Damage to environment which must be avoided during food production (5)
global warming, pollution, deforestation, soil erosion, reducing soil fertility
Limiting factors of plant growth (6)
Light intensity, CO2 concentration, temperature, availability to nutrients, pests and diseases, competition
Intensive farming practices and their effects (3)
Growth of higher yield crops - higher yield cultivar is created or selected and maintained through cultivation
Fertilisers - give increases crop yield
Pesticides - crops are protected from pests, diseases and competition through insecticides, herbicides and fungicides
How is energy lost in a food chain?
Heat, waste and movement
What happens to the light that hits a leaf?
83% is absorbed, 12% is reflected and 5% is transmitted
What do the black bars on an absorption spectrum represent?
light wavelengths that are absorbed
What does an absorption spectrum show?
the wavelengths of light absorbed by different pigments in a leaf
What does an action spectrum show?
the rate of photosynthesis at different wavelengths of light
What is the function of accessory pigments?
to extend the range of wavelengths that can be absorbed
What is the first stage of photosynthesis called?
The light dependent stage
What does light energy do to electrons?
excites them and raises them to a higher energy state
What enzyme turns adp into atp?
ATP synthase
What is energy used for in the first stage of photosynthesis?
to phosphorylate ADP (make ATP)
photolysis of water (splitting of water into hydrogen and oxygen)
What does hydrogen bind to and make in the first stage of photosynthesis?
hydrogen binds to NADP to form NADPH
What is a by-product in stage 1 of photosynthesis?
oxygen
What is the second stage of photosynthesis called?
Carbon fixation or the calvin cycle
What is used in stage 2 of photosynthesis from stage 1?
ATP and NADPH
What does RuBisCO do in stage 2 of photosynthesis?
attach carbon dioxide to RuBP
What forms when carbon dioxide attaches to RuBP in stage 2 of photosynthesis?
3PG
What is 3PG used for?
it is phosphorylated by ATP and joins the hydrogen from NADPH to from G3P
How is G3P formed?
3GP joins with hydrogen from NADPH
What is G3P used for?
to regenerate RuBP and to synthesise glucose
What does the glucose produced in stage 2 of photosynthesis do?
some is converted into starch
some is used to produce energy in respiration
some is converted into cellulose for cell walls
Reasons to alter an organisms genetics (5)
higher yield, increase in nutritional value, resistance to disease/pests, to survive particular environmental conditions, to make it more suitable for harvesting
What is a cultivar?
a plant that has been created or selected intentionally for desirable characteristics which can be maintained through cultivation
What is a plant field trial?
an experimental investigation in an organisms natural environment instead of a lab
What can plant field trails evaluate? (3)
the performance of different cultivars in a range of environments
the effects of different treatments such as pesticides or fertilisers
genetically modified crops
Required when designing plant field trials
careful selection of treatments/variables
replicates (several trial plots increases reliability)
randomisation (where treated and controlled areas are across the plot)
What is inbreeding?
closely related plants and animals are bred for several generations until they breed true to the desired type due to the elimination of heterozygotes
What is inbreeding depression?
an accumulation of homozygous recessive alleles which can be deleterious
can result in loss of vigour, poor general health, reduced size, reduced fertility, reduced yield
What can inbreeding lead to? (2)
loss of heterozygosity
inbreeding depression
How are F1 hybrids produced?
the crossing of 2 different inbred homozygous cultivars
Why are the F2 generation not favourable?
can be too genetically diverse
can lack the improved characteristics seen in the F1
2 forms of genetic technology
genetic sequencing
genetic transformation
What is genome sequencing used for?
can be used to identify organisms that possess particular alleles for a desired characteristic
2 types of weeds
perennial
annual
Properties of perennial weeds (3)
grow for several seasons
sexual and asexual reproduction (vegetative)
storage organs
Properties of annual weeds (6)
grow for one season only sexual reproduction rapid growth short lifecycle high seed output long term viability of seeds
What are the common invertebrate pests of plants?
insects
nematode worms
molluscs
What effects do invertebrate pests cause?
destroy the leaves
reduces the plants ability to carry out photosynthesis/ produce sugar
causes a reduction in vigour and yield of crop
2 ways weeds, pest and diseases can be controlled
chemical and cultural
3 cultural methods of crop protection
ploughing, weeding, crop rotation
What is ploughing and what effect does it have?
turning over the top layer of soil to bury weeds deep enough for them to die and decompose
What is weeding and what effect does it have?
removing weeds should be done early to reduce competion
weeds should also be removed from the edge of the field to prevent a breeding ground for pathogens
What is crop rotation and what effect does it have?
a series of different crops are grown on the same piece of land one after the other over 4 growing seasons
the pathogens in the soil from the first crop cannot grow on the second
2 chemical methods of crop protection
selective pesticides, systemic pesticides
What do selective pesticides do?
absorbs through the leaves speeding up the metabolism of the plant so that they use up all their food reserves and die
have a greater effect on broad leaved plants
What do systemic pesticides do?
spreads through the vascular system of the plant and kill pests feeding on them
5 problems with pesticides
Toxicity, persistence, accumulation (bioaccumulation), magnification (biomagnification), resistant populations
Explain toxicity (problems with pesticides)
pesticides can be poisonous to non-target species and could cause disease such as cancers
Explain persistence (problems with pesticides)
a persistent pesticide is not broken down by the environment, harmful effects are prolonged
Explain bioaccumulation (problems with pesticides)
persistent pesticides pass through food chains and build up in animal tissue, their concentration gets higher
Explain biomagnification (problems with pesticides)
the concentration of persistent pesticides increases at each trophic level and can will harm the larger predators at the top of the food web
Explain resistant populations (problems with pesticides)
some organisms may not be killed by the pesticide (resistant)
when they reproduce they pass on the genes for this resistance
What is biological control?
the control of a pest population through the introduction of one of its ‘natural’ enemies eg predator, pathogen or parasite
What is a problem with biological control?
the control organism could become invasive
What is integrated pest management?
a process for controlling pests while minimising any risks to other organisms
uses a combination of chemical, cultural, and biological control to improve yield
Advantage of IPM
to reduce chemical use
Properties of intensive farming
cost effective
lower costs
higher profits
poorer animal welfare
Properties of free range farming
requires more land
more labour intensive
gets higher price for products
better quality of life
behavioural indicators of poor welfare
stereotypy misdirected behaviour failure in sexual behaviour failure in parental behaviour altered levels of activity
What is stereotypy?
where an animal makes repetitive movements over and over again
often shown by animals in bare or confined enclosures
What is misdirected behaviour?
normal behaviour directed inappropriately towards itself, it’s surroundings or another animal
common in animals kept in isolation
What is altered levels of activity?
animals may show very low levels of activity (apathy)
or
very high levels of activity (hysteria)
What is direct contact? (symbiosis)
when a parasite is passed directly from one host to another when the two hosts come in close physical contact eg head lice
What are resistant stages? (symbiosis)
some parasites can resist drying out and other stresses such as temperature extremes and harsh chemicals
they can survive outside the host for a period of time
What are vectors? (symbiosis)
a vector is an intermediate organism that transfers a parasite from one host to another
What is a secondary host? (symbiosis)
a secondary or intermediate host is necessary for some parasites to complete their life cycle
What is mutualism?
a form of symbiosis which benefits both partner species involved in the interdependent relationship
What is a social hierarchy?
a rank order within a group
What is cooperative hunting?
when a group of animals work together to gain food
Advantages of cooperative hunting (4/5)
- increase in hunting excess rate
- predators can take down larger prey
- the kill can be made more efficiently
- less energy is used per individual
- all predators obtain maximum amount of food possible
What are some social defence strategies and their benefits?
- group organisation to ensure there is a lookout always available: warns group of dangers
- groups can work together to attack a predator: protects offspring
- animals can move together in herds, flocks or schools: more difficult for predators to pick of individuals
- travelling in groups: provides protection for most of herd
What is altruism?
a behaviour which benefits the recipient but harms the donor
common if they are related (kin)
What is kin selection?
when natural selection favours behaviour that increases the survival of relatives as they share many alleles
What is helper behaviour?
help in raising young usually by older offspring
What is reciprocal altruism?
a type of altruism in which the roles of the donor and recipient later reverse
What are social insects?
insects that exhibit social behaviours which means that they live together in large family groups and exhibit a range of complex behaviours
an example - honey bees
What will a social insect society have? (3)
- cooperative care of young insects
- parents and their offspring living together
- the development of a caste system
What is ritualistic behaviour?
repetitive behaviours used to communicate in reproductive and competitive situations
What is appeasement behaviour?
when one animal tries to reduce aggression of another through grooming, hugging or kissing
What are the components of biodiversity that can be measured? (3)
- genetic diversity
- species diversity
- eccosystem diversity
What is genetic diversity?
- the number and frequency of alleles within a population
- the total genetic variability/genetic characteristics of a species
What is species diversity?
a measure of the number of different species in an ecosystem AND the proportion of each species
What is species richness?
a measure of the number of different species in an ecosystem
What is relative abundance?
the proportion of each species in an ecosystem
What is ecosystem diversity?
the number of distinct ecosystems within a defined area
What are some threats to biodiversity?
-overexploitation: harvesting of a natural resource
What is the bottleneck effect?
when a population reduces sharply in number as a result of fire, drought, overhunting or disease
the remaining organisms may be descendants of only a small number of individuals therefore lacking genetic variation
lack of variation means the whole population is susceptible to any change in environmental conditions
What is habitat fragmentation?
when a habitat is divided into several smaller habitats
What causes habitat fragmentation?
- clearing habitats for road building
- agriculture
- urbanisation
What can habitat fragmentation lead to?
a decrease in species richness (reduced biodiversity)
What are habitat corridors?
isolated fragments from habitat fragmentation can be linked
they provide a safe way to get from one place to another and increase access to food and choice of mate
eg bear bridges in banff national park
What is an introduced species?
a non-native species that has arrived in a new geographical area due to human activity either intentionally or accidentally
What is a naturalised species?
when a non-native species spreads within wild communities, becomes established and can maintain its population through reproduction
What is an invasive species?
a naturalised species that can spread rapidly and eliminate native species therefore reducing species diversity
