Common q 2 ~ Flashcards
10, 18, 19
Suggest reasons why a species becomes endangered.
- climate change, habitat destruction, pollution
- hunting by humans for food/sport
- overharvesting, such as fish species or tree species
- introduction of a new species to an ecosystem
What are the disadvantages of captive breeding programmes?
- unusual surrounding is not a suitable environment to be ready to mate
- male and female unresponsive
small: less genetic variation, increased risk of genetic disease, less likely to adapt to changing environment, not enough animals to breed
Why captive-breeding programs might fail?
The dangers which endangered them in the first place are not reduced. Hunting, habitat destruction, overharvesting, introduced species, climate change and pollution.
State different reasons why forest are cut down.
> land for housing and agriculture
logging for paper
mining for fossil fuels or building materials eg: sand and gravel
Outline and explain the likely effect of clearing forests
Soil erosion due to lack of trees to stabilise soil using roots. Soil fills rivers, causing them to flood. Loss of biodiversity. Food web is disrupted. Habitats are lost.
Describe the negative impact of intensive production of livestock in terms of welfare and disease.
Livestock suffer in crowded conditions, leading to poor welfare. Disease spreads easily, and regular antibiotic use promotes bacterial resistance.
Describe the negative impact of intensive production of livestock in terms of food and energy.
Energy is lost between trophic levels, making it more efficient to consume soybeans instead of cattle. The process also requires long-distance transport of feed and energy for temperature control in buildings..
Describe the negative impact of intensive production of livestock in terms of water and waste.
Large quantities of water are provided to large quantities of animals in one place. Water from the surrounding area is used, so animals and plants cannot live there. Waste from livestock pollutes land and waterways.
What are the advantages of intensive livestock farming?
Helps to provide more food –> more cheaply, so fewer people go hungry. Takes up less land, so habitat is left for other species.
State and explain ways in which modern technology has resulted in increased
food production. (besides the three)
Modern technology includes selective breeding allowing us to produce more sheep wool for example. Agricultural machinery is used to work in larger fields.
State and explain ways in which modern technology has resulted in increased
food production. (in terms of the three)
Fertilisers provide mineral ions. Pesticides kill pests to prevent crop destruction. Herbicides kill weeds to reduce competition.
Explain how forests can be conserved.
(education+law)
Education on the importance of forests. Areas of forests are protected by law.
Explain how forests can be conserved.
(sustainability)
Replace cut trees, but conserve primary forests.
Coppicing- trees means the tress are not completely cut, the stump is left to grow. A different part goes through this process every 12 years.
Selective felling is another method where small proportion of the forest is cut.
Explain the advantages of presenting information about food webs as a
pyramid of biomass and not as a pyramid of numbers.
size of the organism is taken into account
better idea of the quantity of energy at each level
Why something is a example of discontinuous variation?
no continuous range of phenotypes
distinct categories
Describe and explain adaptation of hydrophytes.
leaf stalks and stems have air spaces help them float to get plenty of sunlight
stomata on both surfaces, upper in contact for air so carbon dioxide enters through here and oxygen exits here
feathery leaves spread out in water, so that each leave gets plenty of sunlight, helps plant to float, allows strong water currents to flow over without damage
How does nitrogen fixation occur?
by lightning and bacteria in root nodules
Describe the events in the menstrual cycle.
FSH secreted. A follicle with a developing egg in it develops in ovary.
Oestrogen secreted by developing follicle. Causes uterus lining to become thicker and better supplied with blood.
A fully developed follicle causes LH to be secreted, so ovulation occurs.
Describe what happens at ovulation.
An egg is released from the ovary into the oviduct.
Describe what happens during progresterone production.
Follicle develops into a corpus luteum, which secretes progresterone, which keeps the uterus lining thick and spongy, ready to recieve a fertilised egg.
It inhibits the pituatary gland, causing FSH an LH production to decrease, so no more follicles develop in the ovary.
What is the function of the amniotic sac?
a tough membrane that surrounds the developing fetus; encloses amniotic fluid
What is the function of the umbilical cord?
attaches placenta to fetus
What is the function of the muscular uterus wall?
contracts to push the baby out birth canal
What is the function of the cervix/vagina?
dilates during birth, allowing baby through
