question

Discovery of Cyclins

answer

Tim Hunt and Joan Ruderman were studying gene expression in early embryos. While doing so they found three proteins that varied in concentrations at different times of the cell cycle. These were eventually called cyclins. This illustrates that scientists must always be observant, to spot unplanned and surprising discoveries. This example of 'accidental' discovery is common in science.

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Meselson and Stahl Discovery

answer

DNA is semi-conservative (Has one old and one new strand)

question

Meselson and Stahl experiment

answer

Two cultures of E.coli were grown, one with 'heavy' isotopes of nitrogen (^15N) and one with normal isotopes (^14N). After many generations of breeding with these two cultures the DNA of the offspring showed one strand of the 14N and one of the 15N proving DNA is semi-conservative

question

Epidemiology and causes of lung cancer

answer

It is a cancerous growth prone to spreading (metastasising). Caused by one or more carcinogens that enter the lungs in cigarette smoke and other fumes. This cancer has a high mortality rate and must be caught early. It's the leading cause of death in the U.S. Other risk factors include radiation, air pollution, previous lung disease, genetics.

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Symptoms of lung cancer

answer

Short breath, coughing with phlegm, shoulder ; chest pains/aches. Loss of appetite, fatigue and weight loss.

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Epidemiology

answer

the study of the distribution and determinants of health- related states or events (including disease), and the application of this study to the control of diseases and other health problems.

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Light microscope vs. Electron microscope

answer

Light: Cheap, simple, 2000x magnification, dead or alive. Electron:expensive, complex, 500,000x magnification, dead

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How are genes read?

answer

Gene sequencers

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What is the Human Genome project?

answer

A 13 year effort to find and read the human genome.

question

What are key advances in technology for biology?

answer

PCR, computers to automate sequencing and read genome, fluorescent labelling so all four bases can be analysed at the same time, digital cameras to read dye markers.

question

how does PCR work?

answer

the DNA is multiplied many times in a thermocycler to get millions of copies that can then be analysed

question

What was used to discover DNA molecules in chromosomes?

answer

Autoradiography

question

What is autoradiography?

answer

A process where radiation from a substance is captured on a camera.

question

How did John Cairn's use autoradiography?

answer

He injected radioactive form of Thymidine (radio marker) into DNA to expose the film. He did this to show how a bacterium's chromosome is made up of a single circle of DNA and then took photos of the DNA undergoing replication of the base pairs splitting.

question

Why do hydrogen bonds form between water molecules

answer

Due to the cohesive nature of water, this creates a surface tension useful for some organisms e.g Water skaters

question

Cohesive properties of water

answer

Water is attracted to itself, positive end attracts the negative end and they combine. When frozen the bonds freeze and lock up creating ice, also explains water droplets, water skaters and how water moves up plant stems.

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Adhesive properties of water

answer

This is when water molecules attach to plant stems (non-water molecule)

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Solvent properties of water

answer

helps other polar molecules with transportation

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Thermal properties of water

answer

Acts as a heat stabiliser in organisms, a large change in temperature is required to change the temp of an organism. Also can cool by sweat production in humans.

question

Energy flow in ecosystems

answer

Energy is not constantly recycled . The cycles of growth, death, and decomposition show how nature recycles nutrients, but energy pyramids show that energy flows through a system and is lost. This is why new energy must arrive in the form of sunlight in order to keep the system going.

question

How much energy is lost at each trophic level?

answer

90%

question

Explain how natural selection isn't just by chance

answer

Natural selection is a multi-step process. Steps involve chance, such as variation, or which gametes participate in fertilisation etc. The characteristics in a population is not purely up to chance. For example, falcons with excellent vision or dolphins that are capable of echo-location. It's no coincidence that flowers have adaptations suited to their insect pollinators, or that certain bacteria become resistant to the antibiotics we try to fight them with. Natural selection favours useful adaptations and selects against harmful ones in a way that is not based on chance, but on fitness. Heritable changes are passed on from generation to generation, and accumulate over time so that each population either fits its environment, adapts accordingly, or dies out.

question

How Staphylococci bacteria was tested for resistance

answer

the bacterium was introduced into a Petri dish along with strips of paper that has been soaked in different types of antibiotic. When the colonies of bacteria grow close to the disks, they show resistance to the antibiotic, when wide, circles with no bacteria are present, they show that the antibiotic is stopping the bacteria the way it should.

question

Uncertainties to cell theory

answer

Recent findings that have raised questions about cell theory include observations of striated muscle, giant algae, and aseptate fungal hyphae.

question

Striated muscle

answer

skeletal muscle is composed of muscle fibres, these are long fibres that can measure 300mm or more and are therefore much larger than regular cells. In addition to this, each muscle fibre contains hundreds of nuclei

question

Giant algae

answer

These organisms are able to grow up to 100 mm in length yet they are unicellular and contain only one nucleus. Due to their size one would expect them to be composed of many cells.

question

aseptate fungal hypae

answer

fungi are made of thread like structures called hyphae (normal in fungi) divided by septa. However in aseptate fungi these hyphae are not divided into sections, they are uninterrupted tube like structures containing many nuclei

question

Falsification of Vitalism

answer

Friedrich Wöhler made a discovery that falsified Vitalism. Wöhler mixed two inorganic substances, cyanic acid and ammonium. He noticed the formation of urea. He had previously only come across urea crystals in the study of the compounds that are characteristic of urine. For the first time in a controlled setting, an organic molecule was synthesized from inorganic substances. This was soon used as evidence against vitalism Soon after, substances such as amino acids were synthesized from inorganic precursors in various laboratories.

question

Reclassification of the figwort family

answer

The plant was classified into specific categories that included the family Scrophulariaceae, the figwort family. DNA sequencing was done on many species including foxgloves, and it was determined that some plants did not belong with the other figworts but instead belonged in the family Plantaginaceae along with the plantains. Foxgloves now have a new family.

question

Discovery of the circulation of blood

answer

William Harvey determined that the heart acts as a double pump and that the blood is continuously circulated to/from the lungs and to/from the body. Before it was believed that blood was constantly being used up by the body.

question

Non-standard amino acids in proteins

answer

Most, but not all, organisms assemble proteins from the same 20 amino acids . If you include all known living organisms then there are 22 amino acids that are used to create polypeptides. The additional two are called selenocysteine and pyrrolysine.

question

Are all plants/algae autotrophic?

answer

Most but not all

question

Pentadactyl limbs in vertebrates

answer

Darwin explained that homologous structures were not just a coincidence but evidence that the organisms in question have a common ancestor.

question

Monitoring the change in atmospheric gases

answer

Layers found in sheets of ice formed by annual snowfall can be used to study the substances trapped in the layers, such as air bubbles from the year when the layer was deposited. Researchers have collected layers 3000m down, with climate information 400 000 years old. One indication of temperature is the frequency of different types of isotopes found in the air bubbles. Oxygen atoms are usually found in their most abundant isotope, oxygen-16, but can also be found in their 'heavier' form, oxygen-18, which has two extra neutrons. When glaciations happen, the oceans have a slightly higher ratio of oxygen-18, and the glaciers that form have a slightly higher ratio of oxygen-16. By examining these ratios in ice and in the shells of marine fossils, climatologists can trace the colder and warmer periods of the past.

question

Osmosis experiments

answer

They show that accuracy in experiments is particularly important.

question

Why is repetition important in experiments?

answer

to ensure reliability.

question

Gregor Mendel pea experiment

answer

Used artificial pollination in a series of experiments by choosing the pollen of various plants to fertilize other individuals of the same species. He used a small brush to place the pollen on the reproductive parts of the flowers, thus replacing the insects that do it naturally. This technique takes away the role of chance because the experimenter knows exactly which plants are fertilized by which pollen.

question

Mendels results

answer

F2 of Round × wrinkled seeds= 2.96:1,F2 of Yellow × green seeds=3.01:1, F2 ofGreen × yellow pods= 2.82:1, F2 of Tall × short plants= 2.84:1

question

Why is bi-nomial nomenclature used?

answer

groups of scientists: scientists use the binomial system to identify a species rather than the many different local names.

question

How is bi-nomial nomenclature written/typed?

answer

the genus name is capitalized but the species name is not, both are written in italics when typed, or underlined when handwritten,

question

Ethics of stem cell research

answer

In embryonic stem cell treatment the embryo has to be destroyed, since the embryo is becoming a person some people think it is misusing the gift of life. Before 14 days an embryo is not considered a person as it has no nervous system and can still split to form twins. Taking stem cells from an embryo can be considered stopping it normal development into becoming a human.

question

Ethics of Using invertebrates in respirometers

answer

It is tempting to place invertebrates in respirometers to determine oxygen consumption. However, the use of invertebrates in such experiments has ethical implications. It is a living animal and may cause harm to it.

question

Risk of g-mods on the environment

answer

In 1999 a group of researchers carried out a study to find out if the pollen from genetically modified Bt corn could have a negative effect on the larvae of the monarch butterfly. The study was immediately criticized by some members of the scientific community, who claimed that the quantities of transgenic pollen placed on the caterpillar's food was of a concentration that would not be possible in nature, and that more realistic experiments would need to be carried out in the field.

question

Florey and Chain experiment

answer

In 1929 he discovered mould growing on a glass dish in his laboratory which appeared to kill the bacteria he was cultivating. In his follow-up studies, the crude penicillin broth that he had extracted from the mould was non-toxic to rabbits and mice but acted slowly and disappeared quickly

question

Health claims about lipids in the diet

answer

Some lipids are good such as vitamins, saturated fats increase cholesterol, unsaturated fats are good, should make up 10-25% of the daily intake, animal fats are bad.

question

Effects of climate change as a result of humans

answer

More intense and frequent droughts, Flooding, rising sea levels, less food production, more disease, loss of biodiversity, extreme climate conditions

question

How to set up a Mesocosm

answer

Can be in open tanks, but sealed glass vessels are preferable because entry and exit of matter can be prevented but light can enter and heat can leave. Aquatic systems are likely to be more successful than terrestrial ones.

question

How would a quadrat be used by an ecologist?

answer

To estimate the sizes of plant populations by random sampling

question

What components are needed to make an ecosystem?

answer

A community and its abiotic environment

question

Biotic factors

answer

attributes in an ecosystem that refer to living organisms.

question

Quadrat sampling

answer

square or rectangular plot of land, a quadrat, marked off at random to isolate a sample and determine the percentage of vegetation and animals occurring within the marked area.

question

Sustainable communities

answer

communities that are capable of being maintained at a steady level without exhausting natural resources or causing severe ecological damage.

question

Food chains

answer

a feeding hierarchy in which organisms in an ecosystem are grouped into trophic (nutritional) levels and are shown in a succession to represent the flow of food energy and the feeding relationships between them.

question

Light energy

answer

the energy produced or given off directly from the sun causing the growth of plants and the existence of most life forms.

question

Pyramids of energy

answer

a graphical model to show how the energy flows through a food chain, how the amount of energy is decreasing and becoming less available for organisms as it enters each trophic level, and how much of the energy in the ecosystem is lost to the atmosphere as heat.

question

Biomass

answer

the total mass of living matter within a given unit of environmental area.

question

Niche

answer

the role and position a species has in its environment

question

Fundamental niche

answer

The environment that an animal is adapted to naturally

question

Realised niche

answer

The environment that an animal occupies outside of its fundamental niche as a result of lack of resources or habitability

question

Primary succession

answer

An environment where there is life where there was no life before

question

In situ

answer

the natural habitat of an animal

question

ex situ

answer

animals that are not in their natural habitat

question

Deliberate release of alien species example

answer

Savlinia Weevil

question

Accidental release of alien species example

answer

When maori settlers arrived in New Zealand rats where accidentally released from he boats of the settlers.

question

Ecological Succession

answer

Process of change in the species in an environment over time

question

Biomagnification

answer

An increase in concentration of a substance in an animal usually toxic throughout the progression of the food chain

question

Gross production

answer

the amount of chemical energy as biomass that primary producers create in a given length of time

question

Net production

answer

the rate at which all the plants in an ecosystem produce net useful chemical energy

question

Steps of the carbon cycle

answer

1. Carbon enters the atmosphere as carbon dioxide from respiration and combustion 2. CO2 absorbed by producers 3.Primary consumers eat producers 4.Dead consumers and producers decompose in the ground, carbon is retuned to the atmosphere

question

Example of biomagnification

answer

DDT in water to eagles

question

What did DDT cause

answer

Decreased the number of predator birds. The eggs of these birds were easily cracked. In fact, the weight of the mother sitting on the eggs cracked them. It was finally discovered that DDT was building up in the tissue of the birds and interfering with the calcium needed for the shells to be hard

question

What units are used when constructing pyramids of energy?

answer

J m^2 year-1

question

Mesocosm

answer

an experimental tool that brings a small part of the natural environment under controlled conditions.

question

Microplastics

answer

smaller than 5mm, damages digestive systems

question

Macroplastics

answer

greater than 5mm, damages digestive systems

question

Endemic species

answer

Species unique to a geographical area

question

What can competitive exclusion affect?

answer

endemic species

question

How to manage the conservation of areas

answer

Restoration, recovery of threatened species, removal of introduced species, legal protection, funding and prioritising

question

what is richness?

answer

number of organisms

question

what is evenness?

answer

how many of each organism

question

what are the two components of biodiversity

answer

richness and evenness

question

biotic index

answer

the total number of indicator species in a given area

question

indicator species

answer

Species used to measure the conditions of an environment e.g air quality by measuring lichen

question

How can general effect of global warming be prevented

answer

Use fewer fossil fuels, use nuclear power and renewable energy sources such as solar, wind or biofuel, better home insulation, stop deforestation

question

Abiotic factors influencing species distribution in communities

answer

light intensity, atmosphere, water availability, salinity of the soil, soil pH

question

Biotic factors influencing species distribution in communitieS

answer

Other organisms in the ecosystem, inter-relationships between organisms

question

Shelfords law of tolerance

answer

states that the levels of one or more chemical or physical factor determines the abundance and distribution of an organism in an ecosystem

question

Define a Keystone species

answer

A species exhibiting a strong control on the structure of a community

question

Give an example of a keystone species

answer

A sea star pisater

question

Spatial habitat

answer

the area inhabited by an oranges in an ecosystem

question

Feeding activity

answer

What an organism feeds on in an ecosystem to keep the ecosystem in check

question

What interactions between species are there?

answer

Competition, herbivory, predation, parasitism, mutualism

question

What is competition?

answer

When two organisms fight for the same food supply

question

What is herbivory?

answer

primary consumers

question

what is predation?

answer

predators eating consumers

question

what is parasitism?

answer

when an organism lives off of another oragansim

question

what is mutualism?

answer

When two species aid each other in a relationship

question

What are the difficulties in classifying organisms into trophic levels

answer

choosing between secondary and tertiary consumers, omnivores that eat from all trophic levels

question

FCR

answer

measures the efficiency of an organisms ability to take on mass from the food it consumes

question

What principles are follow to make sustainable agriculture?

answer

Maintenance of food, improving the environment, using resources efficiently, improving loves of families and societies

question

secondary succession

answer

when a group of organisms take over a natural primary succession

question

Foredune

answer

No soil, just sand and marram grass

question

yellow dune

answer

thin layer of soil, some animals

question

grey dune

answer

developed layer of humus, further in land

question

humus

answer

organic component of soil from decomposition

question

Mature dune

answer

can support forests, thick humus, wild flowers

question

A human interference with nutrient cycling

answer

overfishing

question

Closed ecosystems

answer

closed systems exchange energy but not matter

question

Biological control

answer

using natural procedures to control unnatural invasive species

question

Biosphere

answer

living organisms on earth

question

Biome

answer

section of the biosphere with distinct characteristics

question

Tundra

answer

high elevation, low temp, low rain

question

Coniferous forrest (taiga)

answer

high elevation, not as cold as tundra, a bit more rain than tundra

question

Temperate forrest

answer

lower elevation, warmer temps, more rain

question

Desert

answer

low elevation, high temperature, no rain

question

Tropical forrest

answer

low elevation, warm temp, moist

question

thermal properties of water

answer

acts as a temperature stabiliser in organisms because it does not change temp quickly, used as coolant in humans during perspiration

question

thermal properties of methane

answer

non-polar, freezing point: -183, boiling point: -163, low energy needed to break bonds, burns

question

how were genetic codes used to prove that archea were unique?

answer

They looked similar to bacteria, and had similar DNA but they didn't have a nucleus, Woese distinguished them from others, they live in harsh conditions

question

What did researchers find was the largest cause of Trisomy-21

answer

age of the mother

question

How was it discovered that x-rays were not entirely safe?

answer

Alice Stewart in the 1950's showed that children whose mothers had prenatal x-rays were twice as likely to die of cancer than children whose mothers didn't

IB Biology SL Nature of Science + Option: Ecology paper 3

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