B4 Flashcards
What is the formula for the capture-recapture method?
Pop size = Total in 1st sample X total in 2nd sample / no. in 2nd sample previously marked
What is zonation?
Where changes in abiotic factors influence the areas in which organisms live
What is the equasion for photosynthesis?
6CO2 + 6H2O —> C6H12O6 + O2
What two scientists looked at photosynthesis and what experiments did they do?
Helmont: Growth not just from soil nutrients
Priestley: Mouse experiments
How did scientists discover the oxygen produced in photosynthesis came from carbon dioxide and water?
They used radioactive oxygen-18, radioactive oxygen is only created when the radiation comes from the water. They found it was a two stage process: Light energy splits water into oxygen and hydrogen ions, then the carbon dioxide combines with the hydrogen ions so glucose and oxygen are formed
Name the layers of a leaf
Waxy cuticle, upper epidermis, palisade layer, spongy mesophyll & vascular bundles, lower epidermis, stomata & guard cells
Why are plants green?
The pigments in chlorophyll mainly absorb purple and red light, so they reflect the opposite - green
What is diffusion?
Net movement of particles from a high to low concentration
How can you increase the rate of diffusion?
- Smaller distance for particles to travel
- Greater concentration gradient
- Greater surface area of cell membrane
What is osmosis?
Diffusion of water from high to low concentration of water through a partially permeable membrane
Why can animal cells swell or shrivel up?
Because water moves in and out through osmosis, but they don’t have an inelastic cell wall to control water content
What are the names for when a blood cell burst and when it shrivels?
Swells (bursts) - Lysis
Shrivels - Crenated
How do young, non-woody plants stay upright?
By having having turgor pressure (water pushing up against the cell wall), if there isn’t enough water the plant becomes flaccid
What happens when plant cells lose lots of water?
Plasmolysis - the inside contracts
What is a xylem and what do they do?
A vascular bundle in plants which transports water and soluble minerals from roots to leaves. Made from dead plant cells and have a hollow lumen.
What is a phloem and what do they do?
A vascular bundle - transports sugars (food) up and down the stem to tissues.
What is transpiration?
The diffusion and evaporation of water from inside a leaf. Water evaporates, water passes by osmosis from xylem vessels into leaf, thread of water inside xylem is pulled up so water enter xylem through root tissues to replace it, and more water enters the root hair cells.
What factors affect transpiration?
Light, air movement (wind), temperature, humidity
How can you measure transpiration?
Put water and roots in a sealed bag then measure mass before and after.
How are plants adapted to not loose too much water?
Position, size and distribution of stomata vary on every plant depending on environment, turgidity of guard cells changes in relation to light intensity and water availability.
When do guard cells open and close?
During photosynthesis they are turgid (open), if there is a lack of water they become flaccid (closed) and prevent water loss
What happens to a plant if there is a lack of nitrates?
Poor growth, yellow leaves. Nitrates are used to make amino acids to form proteins for growth
What happens to a plant if there is a lack of potassium?
Poor flower, dark leaves. Helps enzymes in photosynthesis and respiration.
What happens to a plant if there is a lack of phosphates?
Poor root growth, spotty/discoloured leaves. Make DNA and cell membranes.
What happens to a plant if there is a lack of magnesium?
Yellow leaves. Makes chlorophyll for photosynthesis.
What is active transport and what is it used for?
When a plant needs to absorb something from a low to high concentration (against the gradient). It requires energy from respiration. It’s how plants absorb mineral ions through root hairs.
How can you speed up decay?
Changing temperature (microorganisms work best at 40°C), more oxygen increases respiration, moister conditions for growth
What are detrivores?
Earthworms, maggots and woodlice.
Break substances down to have large surface area so it is easier for microorganisms to break it down (speeds up decay)
What are fungi/how do they work?
They are saphrophytes- they secrete enzymes onto material then absorb the digested products.
How can you preserve food?
Pickling (acid kills microorganisms), sealing to prevent entry, preserve in sugar/ salt removes all water by osmosis, dried reduces moisture, kept at low temps to slow down growth.
What are some examples of intensive farming?
Hydrophonics, fish farms, battery farming, glasshouses
What is an advantage and disadvantage of organic farming?
Advantages: food and environment aren’t contaminated, biodiversity is encouraged and it’s more fair to animals
Disadvantages: expensive, more space needed, less efficient
What is an advantage and disadvantage of hydrophonics?
Advantages: less risk of disease, minerals easily adjusted
Disadvantages: Support needed, expensive fertilisers needed
What is an advantage and disadvantage of biological control?
Advantages: no repeat of treatment, pests can’t become resistant, no need for chemicals
Disadvantges: predator could leave area, predator might not eat pest
