B2.1 Flashcards
What is diffusion?
The net movement of particles down a concentration gradient (high to low concentration)
Passive process
In the body, name 2 uses of diffusion
Oxygen and glucose into cells, carbon dioxide out of cells
How do you increase the rate of diffusion?
Decrease the distance needed to move
Increase the surface area
Increase the concentration gradient
What is osmosis
The diffusion of water particles across a partially permeable membrane from a high water potential to low water potential
Passive process
How is water potential determined?
By the concentration of free water molecules
Pure water has the highest water potential,and the more concentrated a solution is the lower the water potential
Why is osmosis not always a good thing?
It can lead to animal and plant cells becoming burst or crinkled
Match the word to the cell and cause Crenated Plasmolysed Turgid Lysis
Crenated - crinkled animal cell, as it loses water
Plasmolysed - softened and collapsed plant cell, as it loses water
Turgid - firm and rigid plant cell, as it gains water
Lysis - burst animal cell,as it gains water
What is active transport?
The process which allows cells to move substances against the concentration gradient
Active process
Why would you expect root hair cells to have lots of mitochondria?
They absorb mineral ions by active transport. As it is against the concentration gradient, ATP (from respiration) is required. Mitochondria are needed for respiration
What does the ATP in active transport do?
Allow Carrier proteins in the cell membrane to transport substances i.e by flipping over
What are 3 examples of active transport
Plants taking mineral ions from the soil
Nerve cells taking in potassium ions and sodium ions leaving
Glucose being transported to the bloodstream through the villi
What is mitosis?
The process in which body cells divide and duplicate
How can you tell if DNA is being replicated for mitosis, not for transcription
If it is for mitosis, there will be no uracil
How do chromosomes move in mitosis?
After being copied, they line up at the centre
Spindle fibres pull them to opposite ends of the cell
2 nuclei form
What happens after the movement of chromosomes in mitosis?
Cytokinesis - The membrane pinches off to separate the 2 nuclei and creates 2 cells
What is the ‘transition’ stage between mitosis that allows it to be called a cell cycle
The growth of daughter cells
What is cell differentiation
When cells become specialised to perform a particular job
Name and explain the adaptations of some specialised cells in animals
Sperm cells - tail,lots of mitochondria,acrosome to break layers of ovum and transfer genetics
Fat cells - A layer of cytoplasm with fat inside, can expand to x1000 size
Ciliated cells - In airways, goblet cells provide mucus to trap bacteria, cilia sweep them away.
Red blood cell - biconcave,haemoglobin,no nucleus, can easily pass through capillaries
Name and explain the adaptations of a specialised plant cell
Palisade cells - Regular shape for close packing,close to surface of leaf,chloroplasts
What is a stem cell?
Undifferentiated cells which can divide by mitosis, and those cells can differentiate and become specialised
State 2 differences between embyronic and adult cells
Adult cells are used for repair, embryonic for growth
Embryonic can differentiate into all cell types, adult can only differentiate into a limited range of cells
Referring to stem cells, how are humans born?
After the sperm fertilises the egg, a zygote (stem cell) is produced,and it divides and produces all the cells needed to make a person
Where are stem cells found in plants?
Meristems, for example shoot tips
Meristems are the only parts where a plant grows
