Combined Science Flashcards
What is diffusion?
the movement of particles from a high concentration to low.
What is the equation for magnification?
magnification=image/actual
What is a prokaryotic cell?
A cell that does not contain a nucleus e.g. bacteria cell
Why is electron microscope better than a light electron
they have a higher magnification.
they have a higher resolution
Where are the chromosomes found?
they are found in the nucleus
How many pairs of chromosomes are in the human body?
23 pairs
What do chromosomes carry large amounts of?
Genes
What Are the different ways cells can be divide?
Mitosis and Meiosis
Name 1 function of mitosis?
essential for growth and development of multicellular organisms.
It helps for growth and repair.
What type of cell is a haploid cell?
A gamete (it holds half of the genetical material.)
What are the stages of meiosis?
1) DNA replicates
2) they line up at the centre of the cell
3) the chromosomes are pulled apart and splits into 2 cells (the DNA is different)
4) they reline up at the centre of the cell.
5) The arms are pulled away
6) the cell splits in half. these become genetically unique.
What are the steps in mitosis?
The DNA replicates to form 2 copies of chromosomes.
2) one set of chromosomes are pulled to each end of the cell
3) the cytoplasm and membrane divide to form 2 identical cells.
What is active transport?
the movement of substances against their concentration gradient
What was John Dalton structure of an atom?
He described as a ‘solid sphere’ AND different spheres were made up from different elements.
What did Bohr find out? What was his theory supported by?
He found out that all electrons are contained in a shell He proposed they orbited in fixed shells
he did many experiments to prove this theory.
What did Rutherford do to show the plum pudding model was wrong?
The Alpha Particle Experiment
this was sending positive charged particles at a thin sheet of gold foil. he found out that the particles did go through but many deflected and some deflected backwards.
What did JJ Thompson find out?
he found out that atoms were not a solid sphere and shows that their must be a negatively charged particle (electron)
(plum pudding model)
What did Rutherford also found out?
particles that have the same charge as a hydrogen particle were positive (protons)
What experiment did James Chadwick carry out?
An experiment that there were neutral particles (neutrons)
What are the 3 main differences between a plant and animal cell?
plants have cell walls, chloroplasts and permanent vacuole.
animal cell have bones instead of cell wall.
What is the definition of osmosis?
the movement of water molecules from a partially permeable membrane across a high to low concentration
What do 2 gametes form?
Diploid cell
What are the five things that are usually in an animal cell?
Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.
What is a bacteria cells true nucleus?
they have a singular strand of DNA that floats freely in the cytoplasm
What can some bacteria cells sometimes contain?
plasmids
What are the six labels for a light microscope?
Eye piece coarse adjustment knob, high and low power objective lens, fine adjustment knob, stage and light.
What is differentiation?
the process by which a cell changes to become specialised for its job.
Examples of differentiation
sperm cells are specialised for reproduction
nerve cells are specialised for rapid signalling
muscle cells are specialised for contraction
root hair cells are specialised for absorbing water and minerals
phloem and xylem cells are specialised for transporting substances
What are undifferentiated cells called?
stem cells.
Where are stem cells found?
early embryos
What are stems cells used to cure?
different diseases e.g. it can replace faulty cells from stem cells from the bone marrow.
What is the role of the cell membrane?
to hold the cell together and to let stuff in and out of the cell.
What is active transport used for?
used for moving stuff from a low to a high concentration,
What is the job of the lungs?
to transfer oxygen to the blood and remove the waste carbon dioxide from it.
Where does gas exchange happen?
alveoli
What is the function of the villi?
to increase surface area in a big way so that digested food is absorbed much more quickly into the blood.
What do villi have?
a single layer of surface cells
a very good blood supply to assist quick absorption.
What does the xylem transport in the leaf?
water
Where does most of photosynthesis happen?
the palisade mesophyll
What is the role of the stomata?
to let in the carbon dioxide through diffusion.
What happens to the guard cell when it becomes hydrated?
they open up for more diffusion but meaning more water loss.
What other time do guard cells close?
at night because there is no photosynthesis happening.
What does the phloem transport?
sugar molecules
Why does the upper epidermis have to be thin?
so sunlight is able to pass through.
What is the substance on the upper epidermis to help prevent water loss?
waxy cuticle
What is the definition of finite resource?
natural resources that are being used up quicker than they can be produced
what is the definition of renewable resource?
natural resources that are being made and used up at the same rate
examples of finite resources?
limestone, fossil fuels, metal ores
examples of renewable resources
rubber, wood, silk, ethane, cotton, wool
Where can natural resources be found?
The oceans, earths atmosphere, earths crust, rivers, lake
