B1 - Cells Flashcards
(22 cards)
What is diffusion
The movement of particles from a high concentration to a low until they are evenly distributed
3 differences between prokaryotic and eukaryotic cells
Prokaryotes have no nucleus unlike eukaryotes
Prokaryotes don’t have chloroplasts or mitochondria
Prokaryotes are smaller
List the main features of an animal cell and explain their functions
1) Nucleus - contains genetic material that controls the cell
2) cytoplasm - a substance where most of the chemical reactions happen, contains enzymes.
3) Cell membrane - holds the cell together and controls what goes in and out
4) Mitochondria - where most of the aerobic respirations reaction’s happens, transfers energy that the cell needs
5) Ribosomes - where all the proteins are made in the cell
List the main features of a plant cell and explain them
1) rigid cell wall - made of cellulose, it supports and strengthens the cell
2) permanent vacuole - contains cell sap, a weak solution of sugar and salts.
3) chloroplast - these are where photosynthesis occurs, contains chlorophyll which absorbs the light needed.
What is cell differentiation
The process by which undifferentiated cells (stem cells) changes to become specialised for its job
What are stem cells
Undifferentiated cells found in an embryo or an adult bone marrow, also found at the meristem of a plant.
What can stem cells be used for?
Stem cells can be used to cure many diseases by being injected into a patient and having them differentiate to replace faulty cells in the body
Moral problems with stem cells
Currently For stem cell to be obtained the embryo must be aborted.
Risks with stem cells
The cells could be contaminated in the lab with a virus causing the patient to grow even sicker, the body could reject them
How many chromosomes does a healthy human have
23 pairs or 46 chromosomes
What are chromosomes
Coiled up lengths of DNA molecules and genes, they are what differentiate every human
What is the purpose of mitosis/cell cycle for
The growth, development and repair of cells
Explain the steps of the cell cycle
1) DNA is all spread out in long strings
2) the cell grows and increases the amount of subcellular structures such as mitochondria and ribosomes
3) it then duplicates all the DNA and forms X shaped chromosomes with each arm being an exact duplicate
4) the chromosomes line up at the center of the cell and are pulled apart to opposite ends.
5) Membranes form around the two sets of chromosomes and form the two nuclei of the new cells
6) The cytoplasm and cell membrane divide and your left with two new sister cells thats are identical
What is osmosis
Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
Steps for the osmosis sugar solution practical
1) cut a potato into identical shapes and fill multiple beakers with different concentration of sugar solutions (including 0.0)
2) measure the mass of the potato chips using a balance and leave one potato chip in each beaker.
3) after 24 hours take them out ,dry them and measure their mass again.
4) calculate change of mass, if positive then water has been drawn in through osmosis if negative then water has been drawn out.
What is active transport
Substances absorbed against a concentration gradient (from low to high) this often requires energy
Why is active transport used in the body
When there is a low concentration of nutrients in the gut but high concentration in the blood, active transport is used
What does a low surface area to volume ratio mean
A really low Sa:V means that the organism can diffuse and exchange through their surface
Explain why gas exchange happens in the lungs
To transfer oxygen to the blood and to remove waste carbon dioxide from the blood, lungs contain millions of little area sacs called alveoli where gas exchange takes place
Alveoli adaptions to maximise surface exchange
An enormous surface area.
Moist lining for dissolving gases.
Very thin walls.
A good blood supply
Whats the structure that lets CO2 in and oxygen out of a leaf
The stomata is the hole that CO2 diffuses out of and the guard cells are what control the stomata size
What is water potential?
How much water has the ability to move around
