Topic Two Flashcards
Cell and control
In human cells, what is a chromosome?
a structure found in nuclei, containing a DNA molecule
What type of cell division forms two identical daughter cells?
mitosis
In which stage of the cell cycle are the chromosomes duplicated?
interphase
In which stage of the cell cycle, at the end of mitosis, does the one cell divide into two?
cytokinesis
What term describes a cell that has two sets of chromosomes?
diploid
Where are plant meristems found?
tips of plant shoots and roots (also just inside bark of trees)
What happens in a plant meristem?
Cells divide rapidly by mitosis as the plant grows
What happens during cell differentiation?
Cells develop special features that help them carry out a particular function.
Why is cell differentiation important to plants and animals?
Specialised cells are more effective at carrying out different functions in the body.
A root hair cell is a specialised cell. What is its function?
to absorb water and dissolved mineral salts from the soil
How is a root hair cell specialised to carry out its function?
It has a long extension into the soil that increases the surface area for absorption
Explain how one specialisation of a xylem vessel helps it carry out its function.
any one from: thickened wall to prevent collapse of tube/withstand pressure of water; no cell cytoplasm and lost cell walls to form long tubes through which water flows up the plant; small holes in thick cell wall so water can pass into and out of the vessel from surrounding cells
Name one feature, other than mass, that could be measured to show growth in a plant.
any suitable measure that will show change over time, such as: height, tree girth, leaf area, number of leaves
Name the type of cell division that cells use to make identical copies of themselves.
mitosis
What type of cell has the ability to differentiate into specialised cells?
stem cell
In what organ system would you find nerve cells?
the nervous system
Are nerve cells diploid or haploid?
diploid
What part of a nerve cell contains chromosomes?
nucleus
What part of a nerve cell makes proteins?
ribosomes
Nerve cells require a lot of energy. What cell structure would you expect them to have a lot of?
mitochondria
What is a nerve cell specialised to do?
carry electrical signals/impulses
List your senses.
touch, hearing, sight, taste, smell, balance, temperature and plenty of others
State the name of one organ in the nervous system.
brain, spinal cord or nerves or a named sense organ
What type of cells detect stimuli?
receptor cells
In which sense organ would you find receptor cells that detect light waves?
eye
What are the electrical signals used in the nervous system called?
impulse
List, in order, the organs that an impulse goes through from the hand to the brain.
nerve(s), spinal cord
What are the two long ‘arms’ of a sensory neurone called?
dendron and axon
List, in order, the parts of a sensory neurone that an impulse goes through.
dendrite, dendron, axon, axon terminal
Why are sensory neurones so long?
to carry impulses quickly over long distances
What is the name of the fatty sheath that surrounds dendrons and axons?
myelin sheath
What does the myelin sheath do?
speeds up transmission of impulses, insulates neurones from each other
What letters are DNA made up of?
As, Ts, Cs and Gs
What is the structure of DNA?
Double Helix
The double helix is ridiculously long so it is further twisted round to be in a
Chromosone
Where are chromosomes located?
In the nucleus of a cell
In mitosis we go from one parent cell to…
Two identical daughter cells
What is the first thing that happens in mitosis?
The DNA condenses in to chromosomes and lines up down the middle
Once chromosomes have lined up down the middle and checks have taken place, they…
can start to be pulled apart to either end of the cell
What happens when the chromosomes are pulled apart to either end of the cell?
New nuclei will form
What happens after new nuclei forms in mitosis?
They will separate in to two identical daughter cells
What is the order of the stages of mitosis?
Interphase - Prophase - Metaphase - Anaphase - Telephase - Cytokinesis
What is a good acronym to remember the order of the stages of mitosis?
I Party Madly At The Club
What is the advantage of sexual reproduction?
You will get a genetically diverse population which means they are going to be better protected from diseases
What is the disadvantage of asexual reproduction?
You will get a genetically identical population - if a disease comes along and one plant is susceptible, chances are all plants are going to be susceptible too and they will all be wiped out at once
Give 1 advantage of asexual reproduction
Any from there is only one parent meaning that the plant or animal doesn’t have to wait for a mate and their energy is conserved - the parent is putting all of its energy in to conserving its own genes
What is the disadvantage of sexual reproduction?
A mate is required and this can sometimes be hard to find especially in sparsely populated locations
What is cancer?
When cells begin to divide uncontrollably
What does the uncontrollable division of cells lead to?
Lumps which can either be benign tumours or malignant tumours
What are benign tumours?
Things like warts and moles - they are slow and generally harmless
What are malignant tumours?
Fast growing, aggressive and mobile - cells will move throughout your body and cells from the initial lump will jump in to the bloodstream and move somewhere else - they could set up tumours and lumps in other places
A lump on your skin generally could do you a lot of damage/probably won’t do you much damage
Probably won’t do you must damage
A lump on your brain, liver or lungs could do you a lot of damage/probably won’t do you much damage
Could do you a lot of damage
Name 2 risk factors of cancer that we are in control of
Any 2 from smoking, diet, sun and unprotected sex
How is smoking a risk factor of cancer?
Has large implications in lung cancer
How is diet a risk factor of cancer?
A good diet can reduce your risk of bowel cancer whereas if you don’t eat much fruit and vegetables you are putting your bowel at risk of cancer
How is the amount of time we spend in the sun a risk factor of cancer?
Can effect your susceptibility to skin cancer
How is unprotected sex a risk factor of cancer?
Can leave you at risk of cervical cancer
What do stem cells have the potential to do?
Turn into any other type of cell
How can stem cells be used when treating Parkinsons disease?
Grow new brain scells
How can stem cells be used when treating brain and spinal injuries?
Grow new bones to fill the gap
How can stem cells be used to combat organ failure?
Can grow new organs/parts of organs instead of making someone wait on the transplant waiting list
What is the method for making stem cells?
Nuclei removed from egg cell - nuclei from patient cell inserted in to empty egg - egg starts to develop into embryo - stem cells removed from embryo - stem cells turned into new cells
What controversy comes with making stem cells?
Human embryos will be created and destroyed - there are lots of religious objections to this as lots of people say that life starts when embryos are created and people object to the destruction of embryos
The nervous sytem is incredibly complex/simple
complex
What is in the CNS?
The brain and spinal chord as well as all the neurons (receptors and effectors)
What does CNS stand for?
Central Nervous System
What needs to happen when you pick up a stimuli?
That signal needs to travel from wherever you picked it up (your fingers) all the way up to your nervous system
Where will the signal sent after picking up a stimuli sometimes stop?
The spinal chord
What is a reflex?
When you pick up a stimuli and the signal gets sent to your CNS, which then sends the signal straight back
Touching something hot and moving your hand away without thinking about it happens as a result of your…
reflexes
Nerve cell bodies are incredibly short/long
long
What can nerve cells send?
Fast electrical signals
What happens when nerve cells have to send a signal from one nerve cell to another?
Things slow down
Why do things slow down when nerve cells have to send a signal from one nerve cell to another?
They have to cross a synapse
What is sent across a synapse?
A slow chemical signal
Why is crossing a synapse a slow process?
The chemical has to be released, diffused across the channel, get picked up and then initiate another electrical signal
