Cells, Organs And Populations Flashcards
What does a animal cell contain?
Nucleus Cytoplasm Mitochondria Cell membrane Ribosomes
What does a plant cell contain?
Everything in an animal cell
Cell wall
Permanent vacuole
Chloroplasts
What is yeast?
A single celled organism, a microorganism that has a nucleus, cytoplasm and a cell membrane surrounded by a cell wall
What is a bacterial cell?
A single celled microorganism, which has a cytoplasm and cell membrane surrounded by a cell wall. It’s genetic material flits in the cytoplasm as they don’t have a nucleus
How do dissolved substances move in and out of cells?
By diffusion
What kinds of molecules can diffuse through cell membranes?
Oxygen, glucose, amino acids and water
What kind of substances can not diffuse through a membrane?
Starch and proteins
Who are palisade leaf cells adapted for photosynthesis?
- packed with chloroplasts for photosynthesis, which are crammed at the top of the cell so they are nearer to light
- tall shape for a larger surface area exposed down the side of the leaf for absorbing more CO2
- thin shape means they can pack lots of them in at the top of the leaf
How are guard cells adapted to open and close pores?
- kidney shape which opens and closes the stomata
- when the plants have lots of water the guard cells fill with it and become plump and turgid. This makes the stomata open so gases can be exchanged for photosynthesis
- when the plant is short of water, guard cells lose water and become flaccid making the stomata close, this helps to stop water vapour escaping
- sensitive to light and close at night to save water without losing out on photosynthesis
How are red blood cells adapted?
- concave disc shale which gives a big surface area for absorbing oxygen. It also helps them pass smoothly through the capillaries
- packed with Haemoglobin (pigment which absorbs oxygen)
- no nucleus, more room for haemoglobin
How are egg cells adapted?
The egg fell Contains huge food reserves to feed the embryo
-changes its membrane structure when the sperm fuses with the egg so that no more sperm can get in
How are sperm cells adapted?
- enzymes in head to digest through the egg cell membrane
- streamlined head and long tail to swim to the egg
- a lot of mitochondria to provide the energy needed
What are large multicellular organisms made up of?
Organ systems
What is the process by which cells become specialised for a particular job ?
Differentiation
When does differentiation occur?
During the development of a multicellular organism
Specialised cells form …
Tissues, which form organs, which form organ systems
What is a tissue?
A group of similar cells that work together to carry out a particular function
What is a glandular tissue?
A tissue which makes and secretes chemicals like enzymes and hormones , e.g. Digestive juices
What is an epithelial tissue?
A tissue which covers some parts of the body
What is an organ?
A group of different tissues that work together to perform a certain function
What is an organ system?
A group of organs working together to perform a particular function
Name the parts and functions of the digestive system
- Glands (salivary glands and pancreas) produce digestive juices
- The stomach and small intestine, digest food
- Liver, produces bile
- Small intestine which absorbs soluble food molecules
- Large intestine which absorbs water from undigested food, leaving faeces
What does the digestive system do?
Exchanged materials with the environment by taking in nutrients and releasing substances (e.g. Bile)
What is the equation for photosynthesis ?
Carbon dioxide+ water =(sunlight + chlorophyll)= glucose + oxygen
What are the plant organs?
Stems, roots and leaves
What are the tissues in a leaf?
- mesophyll tissue, where photosynthesis occurs in the plant
- xylem and phloem, transport things like water and mineral ions around the plant
- epidermal tissue- covers whole of the plant
How are chloroplasts used for photosynthesis?
They contain a green substance called chlorophyll which absorb sunlight and used its energy to convert carbon dioxide and water into glucose. Oxygen is produced as by-product
What factors affect the rate of photosynthesis ?
Light, CO2, temperature and water
What is a limiting factor?
Stopping photosynthesis from happening any faster
What is one way to control the amount of CO2 in photosynthesis?
Dissolve different amounts of sodium hydrogencarbonate in the water which gives off CO2
How is temperature a limiting factor of photosynthesis?
If the temperature is too low, the enzymes needed for photosynthesis work more slowly. If the plant gets too hot, the enzymes needed will become denatured
How are greenhouses used for photosynthesis?
They trap the suns heat, and make sure the temperature doesn’t become limiting
In winter, heaters can be used and in summer, shares and ventilation may be used to cool things down
Artificial sunlight can be used
Amount of CO2 can be increased by using a paraffin heater
Keeping plants enclosed keeps them away from pests and disease
How do plants use glucose for respiration?
Glucose is used to release energy which enables them to convert the rest of the glucose into other useful substances, which can be used to build new cells and for growth
How can glucose be used to make cell walls?
It is converted into cellulose for making strong cell walls
How can glucose be used for making proteins?
It is combined with nitrate ions to make amino acids, which are then made into proteins
How do plants use glucose to store it as starch?
Glucose is turned into starch and stored in the roots stems and leaves, ready for use when photosynthesis isn’t happening (winter).
What affects where an organism is found?
- temperature
- availability of water
- availability of oxygen, CO2, nutrients
- amount of light
How do you measure how common an organism is in two samples areas?
By using quadrats
Quadrat is placed at a random point within the first sample area and all organisms within the quadrat are counted. This is repeated. The mean number of organisms per quadrat is then worked out within the first sample area. This is repeated in the second sample area
How do you measure how the distribution of an organism changes across an area?
By placing quadrats along a transect
Mark out a line in the area you want to study using a tape measure. Collect date along the line by counting all the organisms that touch the line. OR place quadrats next to eachother along the line or at regular intervals and count the organisms inside
How do you work out population size?
Work out the mean number of organisms per m^2. Then multiply the mean by the total area
