Manipulation of the food species Flashcards
Advantages of high population of both crops and animals
- increased yield
- pest control
- better soil health
- efficient land use
Disadvantages of high population of both crops and animals
- increased competition
- disease spread
- soil degradation
Advantages of low population of both crops and animals
- reduced competition
- lower disease risk
- improved soil health
- enhanced biodiversity
Disadvantages of low population of both crops and animals
- lower yield
- vulnerability to pests
- limited genetic diversity
Optimum population density changes for each farm/area and is dependent on:
- crop type
- soil quality
- water availability
- climate
Definition of a monoculture
1 species covering a fairly large area
low genetic diversity
Advantages of monoculture
- efficient harvesting
- minimal technology
- higher yield
- higher income
Disadvantages of monoculture
- low genetic diversity
- increased disease
- low biodiversity - less stable
Selective breeding description
Agents are selected with desired traits
Offspring then express these desired characteristics
Frequency increases over generations
How have chickens been selectively bred for food consumption
Faster egg production - kept in battery cages, breed the hens which lay the most eggs
Faster meat production - kept intensively in large sheds, chose chickens with higher meat mass
How have cows been selectively bred
For meat - ancestor had mutation ‘double muscling’
Disadvantages - causes difficulties when the cows give birth
Example of selectively bred plant
Wild Mustard Plant - leaves used for kale and flower buds used for cauliflower
Define crossbreeding
2 different varieties of the same species - genetically different
What are the general characteristics of a crossbred hybrid breed
Traits of both parents - e.g. labradoodle
High genetic diversity
Bigger and stronger
Example of a crossbred plant
Different varieties of a tomato
Characteristics: disease-resistant and high yield
Example of a crossbred animal
Zebu (does well in hot climates) + Ayrshire (high milk yield)
Offspring - high milk yield, heat tolerant
What is artificial insemination
Process of injecting a male semen into a females cervix when she is in oestrus
Benefits of artificial insemination
Useful for breeds at risk
Ensures survival of rare gene pools
Diseases are less likely to spread - as women don’t have to be transported to the stud
Describe the process of embryo transfer
Females + hormone FSH
Produce many eggs
Eggs collected and fertilised with desired sperm
Fertilised embryos implanted into surrogates
Define asexual reproduction
Only using one parent for producing offspring identical to the parent
Advantages if asexual reproduction
Occurs quickly
No need for mates
Lower risk of disease
Disadvantages of asexual reproduction
No introduction of new genetics
Vulnerable to environmental change
Overpopulation
2 methods of artificial vegetative propagation
Cutting
Micropropagation
What is cutting
Take a cutting and add a rooting hormone
Then plant the cutting
And it will grow roots
What is micropropagation
Choose a plant with good traits
Sterilise the plant material - add to a nutrient rich gel (agar)
Starts to grow shoots and roots
The shoots separate and encourage more to grow
Plant is moved to a field for further growth
What is the process of cloning
Gather group of cells - placed into a nucleus
They are fused using an electric shock
Fused cells begin to divide normally
Embryo is placed in the uterus of a foster mother
Advantages of cloning
Preservation of endangered species
Research and development
Disease resistant
Disadvantages of cloning
Ethical concerns
Health issues
Reduced genetic diversity
High costs
Define genetic engineering
Deliberate modification of the characteristics of an organism by manipulating its genetic material
Define transgenics
An organism whose genome has been altered by the introduction of one or more foreign DNA sequences from another species
2 examples of GM foods
Rice - disease resistant, insect resistant - high yield
Cotton - insect resistant, herbicide tolerant - disease resistant
Advantages of GM
Increase resistance to specific insects
Increase pathogen resistance
Introduce traits from other species
Disadvantages of GM
Increase costs to farmers
Reduce local indigenous crop diversity
Escaping genes from GM crops into non GM crops
What are auxins and what are they used for
Plant hormones - regulated growth
Root development
Fruit development
What are gibberellins and what are they used for
Promote plant growth
Seed germination
Flowering promotion
What is ethylene and what it is used for
Regulates plant growth
Fruit ripening
Flowering
What are anabolic steroids and what are they used for
Mimic effect if testosterone - promote muscle growth
Medical uses
Physical appearance
What is BST and what is it used for
Synthetic version of a naturally occurring growth hormone
Milk production
Economic benefits
