2a Flashcards
What is the cell membrane?
Supports the cell and controls what goes in and out
What is the nucleus?
Controls activity and contains genetic material
What is the cytoplasm?
Site of chemical reactions which contains enzymes to control the reactions
What is mitochondria?
Site of reactions for respiration
What are the ribosomes?
Where proteins are made in the cell
What is the cell wall?
Supports the cell and structures it
What does the permanent vacuole contain?
Cell sap which is a weak solution of sugar and cells
What are chloroplasts?
Where photosynthesis occurs and they contain chlorophyll
What is the structure of a yeast cell?
Nucleus, cytoplasm, cell membrane and a cell wall
What is the structure of a bacterial cell?
NO NUCLEUS! Cytoplasm, cell membrane, cell wall. The genetic material floats in the cytoplasm
What is diffusion?
Spreading out of particles from an area of high concentration to an area of low concentration
What do animal cells not have?
Cell wall, permanent vacuole and chloroplasts
Where does diffusion happen?
In solutions and gases because the particles are free to move
What affects the diffusion rate?
The bigger the difference in concentration the faster the diffusion rate
What kind of molecules can diffuse through cell membranes?
Small molecules like oxygen, glucose, amino acids and water
What can’t diffuse through cell membranes?
Big molecules such as starch and protein
What is the overall movement called?
Net movement
What are specialised cells?
Cells specialised for their function
How is the palisade leaf cell adapted for photosynthesis?
- Packed with chloroplasts, most are at the top closer to light
- Tall shape resulting in large surface area for absorbing CO2
- Thin so you can pack lots in a leaf
What are guard cells adapted for?
To open and close pores
How are guard cells adapted?
- Kidney shape which opens and closes the stomach in a leaf
- When the plant has lots of water the guard cells fill with it and go plump. This makes the stomata open for gas exchange for photosynthesis
- When the plant doesn’t have much water the guard cells lose water and become flaccid which makes the stomach close. This prevents water vapour from escaping
- Thin outer walls and thick inner walls make the opening and closing work
- Sensitive to light and close at night to save water
What are red blood cells adapted for?
To carry oxygen
How are red blood cells adapted?
- Big surface area for absorbing oxygen and to help them pass smoothly through capillaries
- Packed with haemoglobin which absorbs oxygen
- Have no nucleus for more room for haemoglobin
What are sperm and egg cells specialised for?
Reproduction
How are sperm and egg cells specialised?
- The egg cell contains food reserves to feed the embryo
- The eggs membranes structure changes when the sperm fuses with it to stop any more sperm getting in so the offspring ends up with the right amount of DNA
- A sperm has a long tail and a streamlined head to help it swim to the egg
- A sperm has a lot of mitochondria to give to energy to swim to the egg
What is a tissue?
A group of similar cells which work together to carry out a particular function
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
What is the stomach made up of?
- Muscular tissue which moves the stomach wall to churn food
- Glandular tissue which makes digestive juices to digest food
- Epidermal tissue
What is an organ system found in the human body?
Digestive system which breaks down food
Name some plant organs
Stems, roots and leaves
What are leaves made of?
- Mesophyll tissue - where most of the photosynthesis takes place
- Xylem and phloem - transport things such as water, mineral ions and sucrose around the plant
- Epidermal tissue - covers the whole plant
What is the photosynthesis equation?
SUNLIGHT
Carbon dioxide + water ———-> glucose + oxygen
CHLOROPHYLL
What does photosynthesis produce?
Glucose and oxygen
What is photosynthesis?
The process that produces glucose in plants and algae
What factors affect the rate of photosynthesis?
Carbon dioxide, light and temperature
What affects where organisms are found?
Environmental factors such as temperature and availability of water, nutrients, CO2 and O2 and amount of light
How can you study the distribution of an organism?
Measure how common an organism is in two areas using quadrants
Study how the distribution changes across an area by placing quadrants along a transect
What is a quadrat?
A square frame enclosing a known area to compare how common an organism is in two sample area
How do you calculate the mean number of organisms per quadrat?
Number of quadrats
How do you calculate population size?
Multiply the mean number of organisms per metre squared and times it by the total area of the habitat
What is a transect used for?
To study the distribution of organisms along a line
How do you make your results more reliable?
Use a large sample size
How can you improve the validity of your results?
Control the variables and use random samples
How do plants use glucose?
For respiration Making cell walls Making proteins Stored in seeds Stored as starch
