B1 Flashcards
Nerve cell
Send electrical impulses around the body
Long to cover more distance, has branched connections
Muscle
To contract quickly
Long and contains lots of mitochondria (for energy)
Sperm cell
To get male DNA to the female DNA
Streamlined head, long tail, lots of mitochondria (for energy)
Root hair cell
Absorb water from the soil
A large surface area to absorb more water
Phloem cell
Transports substances around the plant
Pores to allow cell sap to flow
Cells are long and joined end to end
Xylem cell
Transports water through the plant
Hollow in the centre. Tubes are joined end to end
What is diffusion
The spreading out of particles from an area of higher concentration to an area of lower concentration.
Osmosis
The movement of water molecules from an area of high concentration to a low concentration through a partially permeable membrane.
Active transport
Movement of substances against the concentration gradient. Requires energy from respiration.
Equation for image size
Image size = actual size x magnification
Osmosis and potato practical
Potato in sugar solution lose water
Potato in pure water solution will gain water
Where are adult stem cells found
In the bone marrow
Use for stem cells
- replacing faulty blood cells
- making insulin producing cells
- making nerve cells
What is the equation for magnification of the microscope
Magnification of eyepiece x magnification of objective
What do ribosomes do
The site of protein synthesis
What do mitochondria do
Where aerobic respiration takes place
What is the cytoplasm
Jelly-like material where many of the chemical reactions happen
What is the nucleus
Contains genetic material
Controls the cell’s activities
What is the cell membrane
Structure permeable to some substances but not to others. Controls movement in and out of cells
What are chloroplasts
Organelles which contains the green pigment chlorophyll, which absorbs light energy for photosynthesis
What is the cell wall
Strengthens cell and supports the plant
What is a permanent vacuole
Filled with cell sap to help keep the cell turgid
What is and give example of prokaryotic cell
A simple cell with no nucleus- DNA is free in cytoplasm
Example: bacterial cell
What is and give example of eukaryotic cell
A type of cell that has a nucleus
Plant/animal/fungi cells
What are chromosomes
Carry genetic information in a molecule called DNA
Each section of a chromosome that contains the code for the production of a particular protein is called a gene
How many chromosomes do humans have
46
23 pairs
Difference between male and female chromosomes is
23rd pair
Female = XX
Male = YY
When do cells divide
An organism grows
An organism becomes damaged and needs to produce new cells
Where is DNA in a cell
In a cell’s nucleus in structures called chromosomes
What is the cell cycle stages
Cell growth
DNA synthesis- the chromosomes are now double stranded
Further growth occurs and the DNA is checked for errors
Mitosis
The cytoplasm separates- two cells are formed
Temporary cell resting period or the cell stops dividing
What are the steps for mitosis
The cell begins to divide
The DNA replicates to form two copies of each chromosome
The nuclear membrane breaks down. The chromosomes line up across the centre of the cell
One set of chromosomes is pulled to each end of the cell and the nucleus divides
The cytoplasm and cell membrane divide to form two identical cells
What are daughter cells
When a cell divides, the new cells produced is called daughter cells
What examples of diffusion are in biological systems
Leaf
- photosynthesis
Lungs
-air in + out
Liver cells
- urea
What is the rate of diffusion effected by
Concentration gradient
Temperature
Surface area of cell membranes
What is osmosis
The movement of water molecules across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration
