Biology Module 4 Flashcards
What is the definition of a population?
All the organisms of one species in a habitat
Explain Van Helmonts experiment
He decided plants gained mass by taking in water. He dried, weighed, and planted some soil. He planted a willow tree that weighed 2.2kg and added rainwater when it was dry. 5 years later he removed it, it weighed 74.5kg. The soil mass had barely changed. He concluded that as the soil hadn’t gained much mass from another source, the water.
What makes up a community?
Populations of different species in a habitat
What is the equation used to estimate population size?
Population size= number in first sample x number in second sample divided by number in second sample previously marked.
What is an ecosystem?
All the organisms living in a particular area, as well as the non-living conditions EG temperature etc
What is the only thing needed in an Eco system?
An energy source, usually the sun
What are transepts used for?
To investigate the distribution of organisms
What do kite diagrams show?
The abundance and distribution of organisms
What are abiotic factors?
All the non-living, physical factors in an environment, EG light, temperature, water
Why is the distribution of organisms affected by the abiotic factors?
Organisms are adapted to live in certain physical conditions, and many organisms can only survive in the conditions they’re adapted to ed mosquitoes are adapted to live in warm climates so can’t survive cold
What is zonation?
The gradual change in the distribution of species across a habitat
What is biodiversity?
A measure of the variety of life in an area
What does biodiversity include?
Amount of variation between individuals of the same species in an area, the number of different species in an area and the number of different habitats in an area
Why do natural ecosystems have a higher biodiversity than artificial ones?
Because they maintain themselves without any major interference from humans
What is the equation for photosynthesis?
6co2+6h2o>c6h12o6+6o2
Where does photosynthesis take place?
In chloroplasts in plant cells
How do plants use the glucose they make?
Respiration, stored in seeds, making proteins, making cell walls, stored as starch
What did Aristotle conclude about plant growth?
That the only thing touching plants was soil,so plants must grow and gain mass by taking in minerals from the soil
Describe one of priestleys experiments
He put a burning candle in a sealed container, and observed that the flame went out after a short while, and couldn’t be relit. He then placed a burning candle and a living plant in the container. The flame went out after a while, but could be relit after a few weeks.
Describe another of priestleys experiments
He filled a sealed container with exhaled air, he put a mouse in the container and observed that it only survived a few seconds. He filled a other sealed container with exhaled air, and put a living plant in the container and waited a few days. He then put a mouse in the container, which survived for a few minutes.
What did Priestley conclude about the candle experiment?
That the candle must use up something in the container, which made the flame go out, and the living plant must restore the air so the candle could burn again.
What did Priestley conclude about the mouse experiment?
That the mouse couldn’t survive long in exhaled air because breathing had taken something our of the air. He decided that the living plant restored the air, which allowed the mouse to survive for longer.
What was priestleys conclusion of both experiments?
That plants restore something to the air that burning and breathing take out. Today we know this substance to be oxygen, as a product of photosynthesis.
What are the 3 limiting factors that control the rate of photosynthesis?
Not enough light slows down the rate of photosynthesis, too little carbon dioxide also slows it down and the temperature has to be just right.
What is diffusion?
The net movement of particles from an area of higher concentration to an area of lower concentration.
What diffuses through cell membranes?
Simple sugars, water or ions
What does the rate of diffusion depend on?
Distance, concentration difference and surface area
Give the word equation for respiration
Glucose + oxygen > carbon dioxide + water
When does photosynthesis happen and why?
It happens during the day because there’s light available
What do plants do at night?
Plants only respire as there’s no light for photosynthesis, so they take in oxygen and release carbon dioxide.
Give 2 ways plants are adapted for diffusion
Broad- large surface area for gases to diffuse
Thin- carbon dioxide and water vapour only have to diffuse a short distance
What is the purpose of the stomata?
To let gases like co2 and O2 in and out.
What is the role of the guard cells?
They control when the stomata opens and closes, controlling gas exchange.
What do chloroplasts contain?
Chlorophyll and other photosynthesis pigments to absorb light energy.
Why is the upper epidermis transparent?
So that light can pass through it to the palisade layer
What is osmosis?
The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
What is a partially permeable membrane?
A membrane with very small holes in it, the holes are so small that only tiny molecules like water can pass through it.
What is a turgid cell?
When a plant is well watered the cells take in water by osmosis and become plump and swollen.
What is turgor pressure?
When the contents of the turgid cell push against the inelastic cell wall.
What does turgor pressure do?
Supports the plant tissues
What is a flaccid cell?
When the plant has no water, so wilts because the cells lose their turgor pressure
What’s a plasmolysed cell?
A cell where the cytoplasm inside the cell has started to shrink and the membrane pulls away from the cell wall.
What is a lysis?
When an animal cell takes in too much water and bursts
What is crenation?
When an animal cell loses too much water and gets all shrivelled up
What do phloem tubes transport?
Food
What do xylem tubes do?
Carry water and minerals from the roots up the shoot to the leaves in the transpiration stream.
What is translocation?
The movement of food substances around the plant
How to root hairs take in water?
The hairs give the plant a large surface area to absorb water from the cell, there’s usually a higher concentration of water in the soil than in the plant, so water is drawn up by osmosis.
What is transpiration?
The loss of water from the plant
What causes transpiration?
Evaporation and diffusion of water vapour from inside the leaves
What are the benefits of the transpiration stream?
Constant water stream keeps the plant cool, water for photosynthesis, water creates turgor pressure which helps support the plant, minerals needed by the plant are brought in with water
What is transpiration rate increased by?
Increase in light intensity, increase in temperature, increase in air movement, decrease in air humidity
What makes the leaf waterproof?
A waxy cuticle covering the upper epidermis
What do plants in hot climates have?
Fewer and smaller stomata in the underside if the leaf, no stomata in the upper epidermis
What are the 3 main minerals needed by plants?
Nitrates,phosphates,potassium
What happens if a plant doesn’t get enough nitrates?
Its growth will be poor and it will have yellow leaves
What happens if a plant doesn’t have phosphate?
It will have poor root growth and discoloured older leaves
What happens if a plant doesn’t get enough potassium?
The plants will have poor flower and fruit growth and discoloured leaves
Why do plants need magnesium?
It makes chlorophyll needed for photosynthesis
Explain active transport
It uses energy from respiration to help the plant pull minerals into the root hair against the concentration gradient (from low concentrations to high concentrations)
Give an example of a decomposer
Soil bacteria, fungi
What does the rate of decay depend on?
Temperature, amount of water, amount of oxygen
Give an example of a detritivore
Earthworms, maggots, woodlice
What do detritivores do?
They feed on decaying material, breaking it up into smaller pieces, which gives it a bigger surface area for smaller decomposers to work on, which speeds up decay
Give an example of a saprophyte
Fungi
What do saprophytes do?
They secrete digestive enzymes onto the material outside their cells, the enzymes break down the material into smaller bits, which can then be absorbed by the saprophyte
Give ways to stop decomposers
Canning, cooling, freezing, adding salt/sugar, adding vinegar, drying
Give ways intensive farmers reduce energy losses at each stage in the food chain
Herbicides to kill weeds, pesticides to kill pests, battery farming
What are hydroponics often used to grow?
Glasshouse tomatoes
Give advantages of using hydroponics
Mineral levels can be controlled more accurately, diseases can be controlled more effectively
Give disadvantages of using hydroponics
Lots of fertiliser needs to be used, no soil to anchor roots and support the plant
Give some effects of intensive farming on the environment
Removal of hedged destroys habitats, fertilisers can pollute rivers,pesticides disturb food chains, battery farming is cruel
How to pesticides disturb food chains?
Pesticides can also kill bees and ladybirds, which can cause a shortage of food further up the food chain.
What is biological control?
Using living things instead of chemicals to control a pest
Give an example of biological control
Aphids eat roses and vegetables, ladybirds are aphid predators so are released into fields and gardens to keep aphid numbers down
Give advantages of biological control
No chemicals are used so less pollution, less disruption of food chains and less risk to people eating the food, no need to repeat the treatment
Give disadvantages of biological control
Predator might not eat the pest, might eat useful species instead, predators population might increase and get out of control, predator might not stay in the area where it’s needed.
What are some alternatives to intensive farming?
Use of organic fertilisers, crop rotation, weeding, varying seed planting times and biological control
Give advantages of organic farming
Uses fewer chemicals, so less risk of toxic chemicals remaining on food, better for environment as less pollution etc, organic farms have to follow ethical guidelines, so no battery farming
Give disadvantages of organic farming
Takes up more space than intensive farming, labour intensive so food is more expensive, can’t grow as much food
