Biology 2A - cells, organs and populations
- Created by: shona
- Created on: 26-12-12 12:00
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- Biology 2A - cells, organs and populations
- cells
- plant and animal cells have similarities and differences
- animal cell
- a nucleus- contains genetic material that controls the activities of the cell
- cytoplasm- gel like substance where most of the chemical reactions happen
- contains enzymes that control the chemical reactions
- cell membrane- hold the cell together and controls what goes in and out
- mitochondria- these are where most of the reactions of the respiration take place
- respiration releases energy that the cell needs to work
- ribosomes- these are where proteins are made in the cell
- plant cell
- usually has all the bits that the animal cell has but with a few extras
- rigid cell wall- made of cellulose it supports the cell and strengthens it
- permanent vacuole- contains cell sap a weak solution of sugar and salts
- chloroplasts- these are where photosynthesis occurs which makes the food for the plant they contain a green substance called chlorophyll
- animal cell
- yeast is a single celled organism
- yeast is a microorganism
- the cell has a nucleus, cytoplasm and a cell membrane surrounded by a cell wall
- bacterial cells have no nucleus
- bacteria is a single cell microorganism
- the cell has cytoplasm and a cell membrane surrounded by a cell wall
- the genetic material floats in the cytoplasm because there is no nucleus
- plant and animal cells have similarities and differences
- diffusion
- diffusion is the gradual movement of particles from places where there are lots of them to where there are fewer of them
- just the natural tendency for things to move around
- DIFFUSION IS THE SPREADING OUT OF PARTICLES FROM AN AREA OF HIGH CONCENTRATION TO AN AREA OF LOW CONCENTRATION
- happens in both solutions and gases- this is because the particles in these substances are free to move about randomly
- the simplest type is when different gases diffuse through each other- this is whats happening when the smell of perfume diffuses through the air in a room
- the bigger the difference is concentration the faster the diffusion rate
- diffusion is the gradual movement of particles from places where there are lots of them to where there are fewer of them
- specialised cells
- cells are specialised for specific functions so their structure can vary
- palisade cells are adapted for photosynthesis
- packed with chloroplasts more of them are crammed at the top so they are nearer to the light
- tall shape means a lot of surface area exposed down the side for absorbing co2 from the air in the leaf
- thin shape means that you can pack loads of them in at the top of the leaf
- guard cells are adapted to open and close pores
- special kidney shape which opens and closes the stomata in the leaf
- when the plant has lots of water the guard cells fill with it go plump
- this makes the pores open so gases can be exchanges for photosynthesis
- when the plant is short of water the guard cells lose water making the pores close
- this helps stop too much water vapour escaping
- thin outer walls and thickened inner walls make the opening and closing work
- sensitive to light and close at night to save water without losing photosynthesis
- red blood cells are adapted to carry oxygen
- concave shape gives a big surface area for absorbing oxygen also helps them pass smoothly through capillaries to reach body cells
- they are packed with haemoglobin the pigment that absorbs the oxygen
- they have no nucleus to leave more room for the haemoglobin
- sperm and eggs cells are specialised doe reproduction
- the main function of the egg cells is to carry the female DNA and to nourish the developing embryo in the early stages
- the egg cells contain huge food reserves to feed the embryo
- when the sperm fuses with the egg the eggs membrane instantly changes its structure to stop any more sperm getting in
- this makes sure that the offspring end up with the right amount of DNA
- the function of the sperm is to get the male DNA to the female DNA
- it has a long tail and a streamline head to help it swim to the egg there are a lot of mitochondria in the cell to provide the engery needed
- sperm also carries enzymes in their head to digest through the egg cell membrane
- the main function of the egg cells is to carry the female DNA and to nourish the developing embryo in the early stages
- palisade cells are adapted for photosynthesis
- cells are specialised for specific functions so their structure can vary
- cell organisation
- specialised cells
- cells are specialised for specific functions so their structure can vary
- palisade cells are adapted for photosynthesis
- packed with chloroplasts more of them are crammed at the top so they are nearer to the light
- tall shape means a lot of surface area exposed down the side for absorbing co2 from the air in the leaf
- thin shape means that you can pack loads of them in at the top of the leaf
- guard cells are adapted to open and close pores
- special kidney shape which opens and closes the stomata in the leaf
- when the plant has lots of water the guard cells fill with it go plump
- this makes the pores open so gases can be exchanges for photosynthesis
- when the plant is short of water the guard cells lose water making the pores close
- this helps stop too much water vapour escaping
- thin outer walls and thickened inner walls make the opening and closing work
- sensitive to light and close at night to save water without losing photosynthesis
- red blood cells are adapted to carry oxygen
- concave shape gives a big surface area for absorbing oxygen also helps them pass smoothly through capillaries to reach body cells
- they are packed with haemoglobin the pigment that absorbs the oxygen
- they have no nucleus to leave more room for the haemoglobin
- sperm and eggs cells are specialised doe reproduction
- the main function of the egg cells is to carry the female DNA and to nourish the developing embryo in the early stages
- the egg cells contain huge food reserves to feed the embryo
- when the sperm fuses with the egg the eggs membrane instantly changes its structure to stop any more sperm getting in
- this makes sure that the offspring end up with the right amount of DNA
- the function of the sperm is to get the male DNA to the female DNA
- it has a long tail and a streamline head to help it swim to the egg there are a lot of mitochondria in the cell to provide the engery needed
- sperm also carries enzymes in their head to digest through the egg cell membrane
- the main function of the egg cells is to carry the female DNA and to nourish the developing embryo in the early stages
- palisade cells are adapted for photosynthesis
- cells are specialised for specific functions so their structure can vary
- the process in which cells become specialised is called differentiation
- this occurs during the development of multicellular organism
- these specialised cells form tissues which form organs which form organ system
- large multicellular organisms(squirrels) have different systems inside them for exchanging and transporting materials
- this occurs during the development of multicellular organism
- similar cells are organised in to tissues
- these work together to carry out a particular function
- muscular tissue
- contracts to move whatever its attached to
- glandular tissue
- makes and secretes chemicals like enzymes and hormones
- epithelial tissue
- covers some parts of the body( inside the gut)
- tissues are organised into organs
- different tissues work together to perform a certain function
- muscular tissue
- moves the stomach wall to churn up foo
- glandular tissue
- makes digestive juices to digest the food
- epithelial tissue
- organs are organised in to organ systems
- organ systems are groups of organs working together to perform a particular function
- glands(pancreas and salivary glands) produce digestive juices
- stomach and small intestine digest food
- liver produces bile
- small intestine absorbs soluble food molecules
- large intestine absorbs water from undigested food
- specialised cells
- plant structure and photosynthesis
- plant cells are organised into tissues and organs too
- plants are made of organs like stems roots and leaves these organs are made of tissues
- mesophyll tissue
- this is where most of the photosynthesis in a plant occurs
- xylem and phloem
- they transport things like water mineral ions and sucrose around the plant
- epidermal tissue
- this covers the whole plant
- carbon dioxide+ water---> sunlight chlolorphyll--> glucose+oxygen
- photosynthesis produces glucose using sunlight
- photosynthesis is the process that produces food in plants and algae the food produces is glucose
- happens in the chloroplasts
- chloroplasts contain a green substance called chlorophyll which absorbs sunlight and uses its energy to convert co2 and water into glucose oxygen is also produced as a by-product
- photosynthesis happens in the leaves of all green plants this is largely what leaves are for
- plant cells are organised into tissues and organs too
- cells
- palisade leaf cells are grouped together at the top of the leaf where most of the photosynthesis happens
- guard cells are therefore adapted to there function of allowing gas exchange and controlling water loss within a leaf
- red blood cells are an important part of blood
- sperm and eggs are very important cells in reproduction
- the digestive system exchanges material with the environment by taking in nutrients and releasing substances such as bile
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