Studied by 1 person
In which type of cell would you find a cell wall, chloroplasts and a vacuole?
plant cell
What does an animal cell have?
cytoplasm
nucleus
ribosomes
cell membrane
mitochondria
What does the nucleus do?
contains genetic material that controls the activities of the cell
What is the cytoplasm?
gel-like substance where most of the chemical reactions happen. It contains enzymes which control these chemical reactions
What is the cell membrane
holds the cell together and controls what goes in and out
What happens in the mitochondria?
these are where most of the reactions for respiration take place. Respiration releases energy that the cell needs to work
What happens in the ribosomes?
these are where proteins are made in the cell
What does a bacterial cell NOT have?
a nucleus- genetic material floats in the cytoplasm
What is a yeast cell an example of?
a single cell organism
What does a yeast cell have?
nucleus
cytoplasm
cell membrane
surrounding cell wall
How is a leaf cell different from a yeast cell?
leaf cells have chloroplasts and a cellulose cell wall. yeast cells have neither
What is the definition of diffusion?
the SPREADING OUT of PARTICLES from an area of HIGH CONCENTRATION to an area of LOW CONCENTRATION or the NET MOVEMENT of PARTICLES down a CONCENTRATION GRADIENT
What substances can diffuse through cell membranes?
small molecules like oxygen, glucose, amino acids and water
What substances can't diffuse through cell membranes?
big molecules like starch and proteins
What are some examples of diffusion?
the diffusion of oxygen into the cells of the body from the bloodstream as the cells are respiring (and using up oxygen)
the diffusion of carbon dioxide into actively photosynthesising plant cells
the diffusion of simple sugars and amino acids for the gut through cell membranes
When, and in which direction, will diffusion take place in solutions and in gases?
if two solutions are separated by a cell membrane, particles will move from a region of high concentration to a region of low concentration
gases will also diffuse through the air from a region of high concentration to a region of low concentration
How is a leaf cell adapted to carry out photosynthesis?
the leaf has mesophyll tissue
the mesophyll cells contain chloroplasts which can photosynthesise
How are palisade cells adapted for photosynthesis?
packed will chloroplasts for photosynthesis
tall shape means a lot of surface area exposed down the side for absorbing carbon dioxide from the air in the leaf
they are grouped together at the top of the leaf so that they can absorb more sunlight
How are red blood cells adapted to carry oxygen?
concave shape gives a big surface area for absorbing oxygen. it also helps them pass smoothly through capillaries to reach body cells
packed with haemoglobin which absorbs oxygen
they have no nucleus to leave even more room for haemoglobin
How are sperm cells adapted for swimming to the egg?
streamlined head and flagella to help it swim to the egg
there are a lot of mitochondria in the cell to provide the energy needed
carry enzymes in their heads to digest through the egg cell membrane
If a cell has many mitochondria...
it must need a lot of energy, e.g. muscle cell, sperm cell
If a cell has many ribosomes...
it is making a lot of protein, e.g. gland cells which produce enzymes
If a cell has flagella..
it must be able to move, e.g. sperm cells
What is the process by which cells become specialised?
differentiation
What is meant by the term differentiation of cells?
when cells start to divide they are very similar
as the tissues develop the cells change to form particular function
What is a tissue?
a group of similar cells that work together to carry out a particular function
What sort of tissue can you find in mammals?
Epithelial tissue: covers some parts of the body, e.g. the inside and outside of the gut
Muscular tissue: contracts to move whatever its attached to
Glandular tissue: makes and secretes chemicals like hormones and enzymes
What is an organ?
a group of different tissues that work together to perform a certain function, e.g. stomach
What tissues are the stomach made up of and what are their purposes?
Epithelial tissue: covers the inside and outside of the stomach
Muscular tissue: contracts the stomach wall to churn up the food
Glandular tissue: produces digestive juices to digest food
What is an organ system?
a group of organs working together to perform a particular function, e.g. the digestive system breaks down food
What organs does the digestive system include?
glands
the stomach
the liver
the small intestine
-the large intestine
What two glands produce digestive juices?
pancreas and salivary glands
what does both the stomach and small intestine do?
digest food
What does the liver do?
produces bile
What does the small intestine do?
absorbs soluble food molecules
What does the large intestine do?
absorbs water from undigested food leaving faeces
Describe in detail what happens to food as it passes through the digestive system?
the insoluble food is mixed with digestive juices produces by glands
it is digested in the stomach and small intestine
bile produced by the liver is added to the food to help digestion
absorption of the soluble food takes place in the small intestine
water is absorbed by the large intestine
What are the plant organs?
stems, leaves and roots
What are the tissues found in plants?
-Mesophyll tissue- where most of the photosynthesis occurs in the plant
Xylem and Phloem- transport things like water, mineral ions and sucrose around the plant
Epidermal tissue- this covers the whole plant
What is photosynthesis?
the process that produces 'food' in plants and algae. the 'food' it produces is glucose
Name the solution used to test a leaf for starch?
iodine solution
What is the result of iodine test for start
the regions containing starch will turn blue-black
the regions without starch will turn yellow-brown
What does the test for starch show us?
if photosynethsis has occurred
Where does photosynthesis happen?
inside the chloroplasts
What is chlorophyll?
a green substance found in chloroplasts which absorbs sunlight and uses it to convert carbon dioxide (from the air) and water (from the soil) into glucose. oxygen is a by-product
What are the top, middle and bottom layers of a leaf?
top - upper epidermis
middle - spongy mesophyll
bottom - lower epidermis
Where is chlorophyll found?
in the chloroplasts
How is water transported in the plant?
through the xylem
How are sugars transported in plants?
through the phloem
What is the equation for photosynthesis?
Carbon dioxide + Water ---(sunlight)---> Glucose + Oxygen
What is a limiting factor?
something that is stopping photosynthesis happening faster
What are the three limiting factors in photosynthesis?
light
temperature
carbon dioxide
Why do limiting factor graphs 'level off' after a certain point?
because the rate of photosynthesis can only be raised up to a certain point, until something else becomes a limiting factor
At what temperature do the enzymes for photosynthesis become denatured?
45 degrees Celsius
How is light controlled in a green house?
light is always needed for photosynthesis so artificial light can be provided once the sun goes down to give plants more photosynthesis time
How is temperature controlled in a green house?
greenhouses help trap the suns heat and make sure that the temperature doesn't become limiting.
heater may be used during the winter to keep the temperature at the ideal level
shades and ventilation if it's too hot to cool things down
How are carbon dioxide levels controlled in a green house?
increase carbon dioxide levels by using a paraffin heater. as the paraffin burns it makes CO2 as a by-product
How are plants protected from pests and diseases?
kept enclosed in a greenhouse
add fertilizers to the soil as well, to provide minerals for healthy growth
What is the independent variable?
the one being tested, e.g. concentration of carbon dioxide (x axis)
What is the dependent variable?
the one you measure, e.g. usually the volume of oxygen produced (y axis)
What are the four ways in which plants use glucose?
for respiration
making cell walls
making proteins
storage as lipids in seeds
storage as starch
Name three substances used for storage in plants?
starch, fats and oil
How is glucose made from photosynthesis used to make cell walls?
glucose converted to cellulose for making strong cell walls, especially in a rapidly growing plant
