2A,B,C,D- structure and functions in living organisms

Question 1

what are the levels of organisation in organisms?

Answer 1

organelles, cells, tissues, organs, and systems
Organelles:a small, specialized structure within a cell that performs a specific function
Cell: The smallest unit of life, made of molecules
Tissue: A group of cells of the same type that work together
Organ: A structure made of one or more types of tissues that work together to perform a specific function
Organ system: A group of organs that work together to perform a specific function
Organism: An individual living thing that may be made up of one or more organ systems

Question 2

what is the function of the nucleus?

Answer 2

NUCLEUS
* CONTAINS THE GENETIC MATERIAL (DNA) WHICH CONTROLS THE ACTIVITIES OF THE CELL
CYTOPLASM * AASEL-LIKE SUBSTANCE COMPOSED OF WATER AND DISSOLVED SOLUTES
* SUPPORTS INTERNAL CELL
STRUCTURES
* SITE OF MANY CHEMICAL REACTIONS, INCLUDING ANAEROBIC RESPIRATION
CELL MEMBRANE * HOLDS THE CELL TOGETHER, SEPARATING THE INSIDE OF THE CELL FROM THE OUTSIDE
* CONTROLS WHICH SUBSTANCE CAN
ENTER AND LEAVE THE CELL

Question 3

what is the function of the cytoplasm?

Answer 3

CYTOPLASM
* A GEL-LIKE SUBSTANCE COMPOSED OF WATER AND DISSOLVED SOLUTES
* SUPPORTS INTERNAL CELL STRUCTURES
* SITE OF MANY CHEMICAL REACTIONS, INCLUDING ANAEROBIC RESPIRATION

Question 4

what is the function of the cell mambrane?

Answer 4

CELL MEMBRANE
* HOLDS THE CELL TOGETHER, SEPARATING THE INSIDE OF THE CELL FROM THE OUTSIDE
* CONTROLS WHICH SUBSTANCE CAN ENTER AND LEAVE THE CELL

Question 5

what is the function of the ribosomes?

Answer 5

ribosomes are found in the cytoplasm and the site of protein synthesis

Question 6

what is the function of the mitochondria?

Answer 6

MITOCHONDRIA
* SITE OF MOST OF THE REACTIONS INVOLVED IN AEROBIC RESPIRATION, WHERE ENERGY IS RELEASED TO FUEL CELLULAR PROCESSES
* CELLS WITH HIGH RATES OF METABOLISM (CARRYING OUT MANY DIFFERENT CELL REACTIONS) HAS SIGNIFICANTLY HIGHER NUMBERS OF MITOCHONDRIA THAN CELLS WITH FEWER REACTIONS TAKING PLACE

Question 7

what is the function of the cell wall?

Answer 7

CELL WALL
* MADE OF CELLULOSE (A POLYMER
OF GLUCOSE)
* GIVES THE CELL EXTRA SUPPORT, DEFINING ITS SHAPE

Question 8

what is the function of the chloroplasts?

Answer 8

CHLOROPLASTS
* CONTAINS GREEN CHLOROPHYLL
PIGMENTS (TO ABSORB LIGHT ENERGY) AND THE ENZYMES NEEDED FOR PHOTOSYNTHESIS

Question 9

what is the function of the vacuole?

Answer 9

• contains cell sap; a solution of sugars and salts dissolved in water
• used for storage of certain materials
• also helps support the shape of the cell

Question 10

what does a plant cell have that an animal cell doesn’t

Answer 10

chloroplast, cell wall, vacuole

Question 11

what are enzymes?

Answer 11

biological catalysts which speeds up a reaction without being used up itself (afterwards it is unchanged and free to catalyse more reactions). THEY CATALYSE METABOLIC REACTIONS

Question 12

what are enzymes made up of?

Answer 12

proteins

Question 13

how are enzymes made?

Answer 13

genes control the production of enzymes

Question 14

why are enzymes needed?

Answer 14

because temperatures in organisms are low e.g., 37 degrees in humans, and without catalysts, most of the reactions that happen in cells would be far too slow to allow life to go on. Reactions can only take place quickly enough when enzymes are present to speed up the reaction

Question 15

what is the difference between an extracellular enzyme and a normal enzyme (intracellular)

Answer 15

an extracellular enzyme (e.g., enzymes that are secreted in the intestine to break down food) functions outside the cell whereas an intracellular enzyme carries their function out within the cell

Question 16

how do enzymes work? draw a diagram

Question 17

how do enzymes work? describe it.

Answer 17

the molecule that an enzyme acts on is called its substrate. each enzyme has a small area on its surface called the active site. the substrate attatches to the active site of the enzyme. the reaction then takes place and the products are formed. when the substrate joins up with the active site it lowers the energy needed for the reactin to start, allowing the products to be formed more easily. the products formed then leave the active site. Enzymes can also catalyse reactions wehre large molecules are built up from smaller ones. in this case, several substrate molecules attatch to the active site to produce a larger molecule.
KEY POINT- the substrate fits into the active site of the enzyme like a key fitting into a lock- a substrate will only fit into the active site of a particular enzyme - AKA THE LOCK AND KEY MODEL OF ENZYME ACTION - this is why enzyme reactions are specific

Question 18

what factors affect enzymes? why?

Answer 18

rate of reaction cna be increase by - concentration of the enzyme or substrate
factors affecting enzymes:
temperature - as the enzyme is heated up to the optimum temperature, the rise in temperature increases the rate of reaction. this is because higher temperatures give the molecules of the enzyme and the substrate more kinetic energy, so they will collide more often. more collisions mean that the reaction will take place more frequently. HOWEVER, above the optimum temperature, the proteins begin to break down and above 40 degrees (in humans for example) the enzyme is denatured which changes the shape of the active side so the substrate will no longer fit into it. this is permanent
pH- the pH inside cells is neutral so most enzymes have evolved ot work best at this pH. At extremes of either side of the pH, the enzyme activity decreases and the active site can shange shape so it is denatured

Question 19

draw a rate of enzyme reaction- temp/pH graph

Question 20

what chemical elements are present in carbs?

Answer 20

carbon, hydrogen, and oxygen

Question 21

what chemical elements are present in proteins?

Answer 21

carbon, hydrogen, nitrogen, oxygen, and sometimes sulfur

Question 22

what chemical elements are present in lipids (fats and oils)?

Answer 22

carbon, hydrogen, and oxygen, but they can also contain other elements like nitrogen, sulfur, and phosphorus

Question 23

what is the structure of carbs?

Answer 23

large molecules made up of smaller basic units: starch and glycogen from simple sugars

Question 24

what is the structure of proteins?

Answer 24

large molecules made form amino acids

Question 25

what is the structure of lipids?

Answer 25

large molecules made up of smaller basic units from fatty acids and glycerol

Question 26

what is diffusion?

Answer 26

the net movement of particles from an area of high concentration to an area of low concentration, down a concentration gradient

Question 27

what affects the rate of diffusion?

Answer 27

the concentration gradient (if it is steep it will happen more quickly)
the SA:VOL ratio (larger surface area to volume means it will increase)
Distance (decreases if distance is greater)
Temperature (higher the higher the temperature because the particles are provided with more kinetic energy)

Question 28

what is active transport?

Answer 28

the movement of substances against a concentration gradient, using energy from respiration
e.g,. glucose is absorbed in the gut into cells lining the intestine as the large protein molecules use ATP to ‘pump’ the glucose

Question 29

what is osmosis?

Answer 29

the net movement of water from a dilute solution to a more concentrated solution (high water potential to a low water potential) across a partially permeable membrane

Question 30

why is cell differentiation important in the development of specialised cells?

Answer 30

after a zygote goes through mitosis, and the cells are copied, the cells become specialised in order to carry out a particular role. This specialisation is under control of the genes and called differentiation. Depending on where it located int he embryo a nerve cell in the spinal cord or an epidermal cell in the outer layer of the skin could be made. Cell differentiation is a vital process in the development of specialized cells because it allows cells to create unique structures and perform specific functions
(Cell differentiation is how cells develop the structure and characteristics needed to be able to carry out their functions Specialised cells are those that have developed certain characteristics that allow them to perform particular functions. These differences are controlled by genes in the nucleus)

Question 31

how are red blood cells adapted?

Answer 31

Red blood cells transport oxygen efficiently due to their biconcave shape, increasing surface area for oxygen diffusion
They contain haemoglobin and lack a nucleus, maximizing space for oxygen transport

Question 32

how are Ciliated cells adapted?

Answer 32

Ciliated cells move mucus in the trachea and bronchi
They have hair-like extensions called cilia, which beat to transport mucus and trapped particles toward the throat

Question 33

how are nerve cells adapted?

Answer 33

Nerve cells conduct impulses and are long, allowing communication between different parts of the body and the central nervous system
Their axons are covered in a fatty sheath that insulates and speeds up nerve transmission. the axon is very long

Question 34

how are Root hair cells adapted?

Answer 34

Root hair cells absorb water and mineral ions from the soil
Their long extensions increase surface area for maximum absorption, and their thin walls help water move quickly through them

Question 35

how are Palisade mesophyll cells adapted?

Answer 35

Palisade mesophyll cells perform photosynthesis and are column-shaped to maximize light absorption
They contain numerous chloroplasts and are tightly packed beneath the upper epidermis of the leaf to optimize photosynthesis

Question 36

how are smooth muscle cells adapted?

Answer 36

elongated to be able to contract to move food through the gut

Question 37

how are xylem vessels adapted?

Answer 37

dead, hollow cell with strengthening walls to be able to carry water up the stem

Question 38

how is the sperm cell adapted

Answer 38

tail for swimming, digestive enzymes int he head

Question 39

what is a stem cell?

Answer 39

a cell that has the ability to divide many times by mitosis while remaining undifferentiated

Question 40

what are the two types of stem cells in humans?

Answer 40

embryonic stem cells - found int he early stages of development int he embryo and can differentiate into any type of cell
Adult stem cells- found in certain adult tissues such as bone marrow, skin, and the lining of the intestine. the have lost the ability to differentiate into any type of cell but can form a number of specialised tissues
e.g., bone marrow can only produce different types of red and white blood cells

Question 41

what are the pros and cons of using stem cells in medicine?

Answer 41

pros:
it can be used to treat or prevent a disease, or to repair damaged tissue (stem cell therapy) e.g., bone marrow transplants which can be used to tread leukaemia which helps replace cells lost during chemo. it has been successful for over 30 years
embryonic stem cells can also be used if obtained from fertility clinics if the parents want to donate them. They can be used to cure Parkinson’s and diabetes, aswell as repair damage from nerve tissue
cons:
moral/ethical issues (they view the use of embryonic stem cells as ‘killing’ an embryo)
a risk of rejection by the body’s immune system, as well as a risk of the stem cells turning into cancer cells.
The body’s immune system rejecting the stem cells