B.2 Scaling Up Flashcards
What is diffusion?
Net movement of particles from a higher to lower concentration
Do the particles move up or down a concentration gradient (diffusion)?
Down
What is an example of diffusion in the human body?
Glucose and oxygen diffusing into cells
What factors affect rate of diffusion?
Distance for particles to move
Surface Area
Increase concentration gradient
What is concentration gradient?
A concentration gradient exists when there is a region of high concentration leading to a region of low concentration
What is osmosis?
The diffusion of water molecules across a semi permeable membrane from a higher water potential to a lower one
What is water potential?
Concentration of free water molecules
What is active transport?
Allows cells to move substances from an area of low concentration to an area of high concentration. As particles are moving against their concentration gradient, energy has to be transferred from an energy store (ATP from respiration)
What do cells which carry out a lot of active transport contain?
Lots of mitochondria
What does mitochondria allow them to do?
Respire rapidly to produce larger amounts of ATP
Active transports rate depends on…?
Rate of respiration to produce ATP
What are carrier proteins?
Special protein that stretch across width of cell membrane.
Molecules bind to the protein and the protein uses ATP to release the molecule inside the cell
What is an animal example of active transport?
During digestion.
Small intestine carbohydrates are broken into glucose. Glucose in actively transported into the bloodstream through villi
What is a plant example of active transport?
Taking minerals from the soil, root hair cell moves nitrate ions across cell membrane and into root cell
What is the size order for:
DNA, chromosone, gene , nucleotide
nucleotide
Gene
DNA
Chromosone
What is mitosis?
Body cells divide into two identical daughter cells.
Why is mitosis used?
To replace and repair and asexual reproduction
What are the four stages of the cell cycle?
DNA replication
Movement of chromosomes
Cytokinesis
Growth of daughter cells
What is cytokinesis?
Cytoplasm dividing
How do the chromosomes move?
They line up along the middle and because they have been replicated, copies of each pull to either end of the cell
What does differentiation mean?
Specialised for a specific job, its structure changes so it is better adapted to perform its function
Name 3 examples of cells which have become specialised
Sperm
Fat
Red blood cell
How has the sperm cell been specialised?
A flagellum so it can swim
Lots of mitochondria for energy
Acrosome, break down outer layer of ovum
How had the fat cell been specialised
Specialised to store fat, can expand massively
Why else are fat cells good?
Insulation and protective
How has a red blood cell been adapted?
Biconcave disks - increase surface area , speeds up diffusion
Full of haemoglobin
No nucleus so there is more space for haemoglobin
Name a plant cell which has been adapted?
Palisade cell
How is the palisade cell specialised?
For photosynthesis. Near surface of leaf, packed full of chloroplast
What are stem cells?
Cells which can divide into any type of specialised cell
What are the two types of stem cells?
Adult stem and embryonic
What is the difference between embryonic stem cells and adult stem cells?
Embryonic can differentiate into any cell
Adult stem cells can only dive into various body cells
Where are stem cells found in plants?
Meristems
Explain gaseous exchange?
Capillaries have a high concentration of carbon dioxide and a low concentration of oxygen, alveoli as the opposite so both move from their higher to lower concentration by diffusion
What transports deoxygenated blood to the lungs?
Pulmonary artery
What transports oxygenated blood back to heart from lungs?
Pulmonary vein
What transports oxygenated blood from heart to body?
Aorta
What transports deoxygenated blood back to body?
Vena cava
What are the differences between a capillary, artery and vein?
Artery - Tick outer layer, small lumen
Capillary - Very small lumen, wall made out of singe layer of cells
Vein - Big lumen and thin walls
What does the xylem do?
Transports water and mineral ions from roots to stem ( upwards motion ) Transpiration
What does the phloem do?
transports dissolved sugars all around the plant. Translocation
What is the structure of the xylem?
Xylem vessels are made from dead xylem cells, no cell walls
What is the structure of the phloem?
Made of living cells. They have sieve plates which have small holes
How does water enter the xylem?
Water diffuses from the soil into root hair cells by osmosis
How is water lost from leaves?
The stomata on the surface of leaves. Uses guard cells to allow the stomata to open and close. When open, water vapour diffuses out
What is plant wilt?
When the plant loses water faster than it takes it in
What factors affect the rate of transpiration?
Light intensity
Temperature
Air movement
Humidity
