B1 Flashcards
What are eukaryotic cells
They are complex and include all animal and plant cells
What are prokaryotic cells
Small and simpler cells e.g bacteria
Name the five subcellular structures of an animal cell
Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
Define the nucleus
Contains genetic material that controls the activities of the cell
Define cytoplasm
Gel-like substance where chemical reactions happen. It also contains enzymes to control the chemical reactions
Define cell membrane
Holds cell together and controls what goes in and out of
Define mitochondria
Reactions for aerobic respiration take place here and respiration transfers energy that cell needs
Define ribosomes
Where proteins are made in the cell
Define ribosomes
Where proteins are made in the cell
Name the three things that a plant cell has that animal cells don’t
Cell wall, permanent vacuole, chloroplasts
Define cell wall
Made of cellulose and supports and strengthens cell
Define permanent vacuole
Contains cell sap
Define chloroplasts
Where photosynthesis occurs which makes food for the plant. They contain chlorophyll which absorbs light
Name subcellular structures of bacterial cells
Cytoplasm, cell membrane, cell wall, a singular strand of DNA and plasmids (small rings of DNA)
What do bacterial cells not have
Chloroplasts, mitochondria and a true nucleus
What do light microscopes use
Light and lenses
What do electron microscopes use
Electrons for higher magnification
What microscope has a higher resolution
Electron microscope
What can electron microscopes see that light microscopes can’t
Ribosome and plasmids
What is the formula for magnification
Image size = magnification x real size
How to convert micro metres to millimetres
Divide by 1000
How do you prepare a slide
1) drop of water in middle of clean slate
2)cut up onion and separate into layers
3) use tweezer to place one layer on slide
4)add drop of iodine solution this highlights the object
5)place cover slip on top
How do you use a light microscope
1) Place slide on stage
2) put stage the lowest with lowest powered lens
3)pull stage up until roughly in focus
4) adjust focus with fine adjustment knob until clear image
5) if you need more magnification swap lens and refocus
Define differentiation
Process by which a cell changes to become specialised for its job
When is an animal cell able to differentiate
At a early stage
When is a plant cell able to become specialised
Always
Why do cells differentiate in mature animals
For repair and replacing cells
What are undifferentiated cells called
Stem cells
What are sperm cells for
Reproduction
Function of sperm cell
To get male DNA to female DNA
How has the sperm cell adapted to help it swim to the egg
Long tail, streamlined head, lots of mitochondria to provide energy, carries enzymes in its head to digest through egg cell membrane
What are nerve cells specialised for
Rapid signalling
What is the function of nerve cells
To carry electrical signals from different parts of the body
How are nerve cells adapted
Long (to cover more distance), branched connections at ends to connect to other nerve cells to make a network throughout the body
What are muscle cells specialised for
Contraction
What is the function of muscle cells
To contract quickly
How are muscle cells adapted
Long so they have space to contract, contain lots of mitochondria to generate energy needed for contraction
What are root hair cells specialised for
Absorbing water and minerals
How are root hair cells adapted
On surface of plant roots and stick out into the soil for a big surface area for absorbing water and mineral ions from the soil
What are phloem and xylem cells specialised for
Transporting substances
What do phloem and xylem cells form
Tubes
What do phloem and xylem tubes transport around the plant
Food and water
How are phloem and xylem tubes formed
They are long and joined end to end
Why are xylem cells hollow
So stuff can flow through them
Why do phloem cells have few subcellular structures
So stuff can flow through them
Define chromosomes
Coiled up lengths of DNA molecules
Where are chromosomes found
In the nucleus
What do chromosomes carry
Large number of genes
What are genes
They define the development of different characteristics e.g. hair colour
How many pairs of chromosomes are there in each cell
There are 23 pairs (46 chromosomes altogether) in each pair one is from the father and one from the mother
What is the process of when the cell divides called
Mitosis
Why do multicellular organisms use mitosis
To grow or replace cells that have damaged
What are the main stages in the cell cycle
Growth and DNA replication and mitosis
What happens in growth and DNA replication
1) DNA is spread out in long strings
2)cell friend and increases subcellular structures e.g. mitochondria and ribosomes
3)it duplicates its DNA and forms X-shaped chromosomes (46 pairs)
What happens during mitosis
1) Chromosomes line up at centre and cell fibre pull them apart and they go to opposite ends of the cell
2) membranes form around each of the sets of chromosomes (nucleus)
3)the cytoplasm and cell membrane divides
Where are stem cells found
Human embryos, bone marrow(can only turn into blood cells)
What are stem cells used for
Medicines and research
What are the risks for using stem cells in medicine
Stem cells from lab could be contaminated with virus and passed to patient
How are adult stem cells used to cure disease
They can replace faulty blood cells
Why are people against stem cell research
They embryo has a potential human life
Where are stem cells found in the plant
Meristems
What can stem cells from plants do
Produce clones for whole plants quickly and cheaply, grow plants of a rare species, grow crops of identical plants that’s have desired features for farmers
Define diffusion
It is the net movement of particles from a high concentration to a low concentration until evenly spread
What happens when the concentration gradient is bigger
The rate of diffusion is faster
How does a higher temperature give a faster diffusion rate
The particles have more energy so move around faster
How do dissolved substances move in and out of cells
Diffusion
Why can’t starch and proteins fit through a membrane
The particles are too big to diffuse
What molecules can diffuse through a membrane
Oxygen, glucose, amino acids and water
What does a larger surface area of the membrane cause
A faster diffusion rate because more particles can pass through at once
