B4 - It's A Green World Flashcards
Describe four different population counting methods.
- Pooters - Nets - Pitfall traps (animal fall into trap) - Quadrats (population is counted for small area, and then scaled up for larger estimate).
Describe the effect of sample size on the accuracy of an estimate of population size.
The bigger the sample size, the more accurate the estimate of the total population is likely to be.
When using the capture-recapture method, what assumptions need to be made?
- No death, immigration or emigration - Identical sampling methods used - Marking won’t affect survival rate
What is the formula to estimate population based on the capture-recapture method?
Population Size = (number in first sample x number in second sample) / (number in second sample previously marked)
What is the difference between a habitat and an ecosystem?
- Habitat is where organisms live, - BUT, ecosystem is all of the different interactions between all organisms and abiotic factors (e.g. temperature, soil quality, e.c.t.).
Explain what it means for an ecosystem to be described as self supporting in all factors other than an energy source.
All of the nutrients, water and essential elements (e.g. carbon and nitrogen) are all recycled within the ecosystem. This allows the ecosystem to sustain itself internally. However, the ecosystem doesn’t provide its own energy source - it gets its energy externally from the Sun.
What is the difference between a community and a population?
A community is made up of different interacting populations in the same ecosystem. A population is all of the organisms of the same type/species living in the same place.
What is zonation?
Zonation is the gradual change in the distribution of species across a habitat.
Explain how a gradual change of an abiotic factor can result in the zonation of organisms in a habitat.
- If the abiotic factors gradually change over a habitat, only certain organisms will be adapted to survive and compete in certain zones of the habitat. For example, if salinity decreases gradually across a habitat, marram grass will grow at the start because they are adapted to survive in salty (saline) conditions. However, as we progress through the habitat, other plants such as lichens and mosses will appear as they are better adapted to less saline conditions.
Compare the biodiversity of native woodlands to forestry plantations.
Native woodlands: - Variety of tree species - Trees different sizes and ages - Variety of plant species - Variety of habitats - Variety of animal species Forestry plantations: - One species of tree planted for timber. - Many trees same age, as many planted at same time. - Fewer plant species; trees are densely planted, so less room and light for other plants. - Fewer habitats because there are less plant species to create them. - Fewer animal species because fewer habitats and fewer sources of food.
Compare the biodiversity of lakes to fish farms.
Lakes: - Many different fish species - Variety of plant species - Variety of animal species Fish farms: - One species that is farmed for food - Fewer plant species because fish food causes algal blooms, blocking out light and killing plants. - Fewer animal species due to a lack of food and fewer habitats.
What is the balanced symbol equation for photosynthesis?
6CO2 + 6H2O –> C6H12O6 + 6O2
Describe the development of the understanding of the process of photosynthesis.
- Greek scientists find plants gain mass, but think this is only because plants take in minerals from soil. 2. Van Helmont’s experiment proves minerals cannot be the sole reason for mass growth in plants. 3. Priestly’s experiment showed oxygen is produced by plants.
Describe photosynthesis as a two stage process.
- Light energy used to split water molecules, releasing oxygen gas and hydrogen ions. 2. Carbon dioxide gas combines with hydrogen to make glucose.
How did we prove that oxygen produced by photosynthesis came from the water and not the carbon dioxide?
- Scientists supply plants with water containing an isotope of oxygen (different form). 2. Carbon dioxide contained ordinary (not isotope) form of oxygen. 3. When plants photosynthesized, they released the isotope form of oxygen. 4. This showed that oxygen came from water, not the carbon dioxide.
Describe the conversion of glucose and starch to other substances in plants and their use:
- Glucose used for energy (respiration). - Glucose turned into cellulose for cell walls. - Glucose used to build proteins for growth and repair. - Glucose turned into starch, fats and oils, for storage.
Describe and explain the potential limiting factors for photosynthesis.
- If there’s not enough light, the rate of photosynthesis is limited. This is because light provides the energy to split water molecules in the reaction. 2. CO2 is also needed for photosynthesis, so if it is not in plentiful supply, it may limit the reaction. 3. If CO2 and light are in plentiful supply, temperature must be the limiting factor. If the temperature is too high, enzymes will denature and the rate of photosynthesis decreases. On other hand, if the temperature is too low, enzymes won’t have enough energy to work.
Explain why plants take in carbon dioxide and give out oxygen during the day and do the reverse at night.
During the day, plants are photosynthesizing due to the presence of sunlight. As a result, they are taking in carbon dioxide and releasing oxygen into the atmosphere. On the other hand, at night, no photosynthesis is taking place. As a result, plants are only respiring - meaning they are taking in oxygen and releasing carbon dioxide.
How and where is light energy absorbed by plants?
Chlorophyll pigments in chloroplasts absorb light energy for photosynthesis.
Why aren’t chloroplasts found in all plant cells?
Chloroplasts are only needed by the plant cells which are involved in photosynthesis - usually located in the leaves and other areas exposed to light from the Sun.
Explain how the cellular structure of a leaf is adapted for efficient photosynthesis:
- Epidermis is transparent so that light can pass through it to the palisade layer. - Most chloroplasts are found in the palisade, because that is the top part of the leaf that receives the most light. - The air spaces in the spongy mesophyll layer allow gases such as CO2 and O2 to move between the stomata and photosynthesizing cells. - There’s a large internal surface area to volume ratio that makes the exchange of gas more efficient.
Explain how leaves are adapted for efficient photosynthesis
- Broad surface area; large surface area for gases to diffuse. - Thin, so short distance for gases to diffuse. - Contain chlorophyll and other pigments to absorb light from different parts of the spectrum. - Network of vascular bundles for support and transport. - Guard cells open and close the stomata, allowing leaves to control gas exchange.
What are vascular bundles? What is their function?
They are the transport vessels, the xylem and phloem, that allow nutrients, glucose and water to be transported. Furthermore, they support the leaf structure.
How do chlorophyll pigments help maximize the use of energy from the sun?
- Light comes to Earth in different wavelengths. - Different chlorophyll pigments absorb different wavelengths of light. - Leaves contain a variety of different chlorophyll pigments, allowing them to absorb a greater portion of the light available.
Explain the movement of particles via diffusion.
- Individual particles move randomly. - If there is a higher concentration of these particles on one side, and a lower concentration on the other, the randomness means that the net movement of particles will be toward the area of low concentration. - While particles are moving in both directions, there are more particles available to move toward the area of high concentration than there are in the other direction.
What factors may increase the rate of diffusion?
- A shorter distance for particles to travel. - A greater concentration gradient. - A greater surface area for diffusion to take place.
How do molecules enter and leave cells?
Diffusion via the cell membrane.
What is osmosis?
Movement of water across a partially-permeable membrane from an area of high water concentration to an area of lower water concentration. - A consequence of random movement of particles (see diffusion flashcard).
What is a partially permeable membrane?
A membrane that allows some molecules (e.g. water) to diffuse through but not others.
How do plants use water from osmosis to support their structure?
- Water enters cells via osmosis. - Water pressure acts against the inelastic cells walls; this is called turgor pressure. - As a result, cells become turgid (plump and swollen). - This gives plants a strong structure.
Why do plants wilt?
- Not enough water enters via osmosis. - Less water pressure, therefore less turgor pressure inside cells. - As a result, the plant cells become flaccid. - This is why the plants wilt or droop.
Explain how leaves are adapted to increase the rate of diffusion of carbon dioxide and oxygen.
- Leaves are broad so they have a large surface area for gases to diffuse. - They are thin, increasing the rate of diffusion. - Lower surface full of little holes called Stomata, allowing gases such as oxygen and carbon dioxide in and out. - Air spaces in spongy mesophyll layer create a large internal surface area to volume ratio, increasing the rate of diffusion.
