sb1 key concepts of biology (paper 1 and 2)

Question 1

what are the stages of preparing a slide

Answer 1

• put on the slide
• thin layer of tissue
• add iodine to colour the cells
• add the colour slip

Question 2

purpose of the nucleus

Answer 2

controls the cells activities

Question 3

purpose of the cytoplasm

Answer 3

where chemical reactions take place

Question 4

purpose of the cell membrane

Answer 4

controls what goes in and out of the cell

Question 5

purpose of the mitochondria

Answer 5

• provides energy
• in the form of atp
• and the site of aerobic respiration

Question 6

purpose of the ribosomes

Answer 6

• processes protein synthesis

Question 7

purpose of the cell wall

Answer 7

• supports and strengthens the cell

Question 8

purpose of the vacuole

Answer 8

• stores cell sap (excess water)

Question 9

purpose of the chloroplasts

Answer 9

• the site of photosynthesis

Question 10

compare plant and animal cells

Answer 10

• similarities: ribosomes, nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
• differentces: plant cells have a cell wall, chloroplast, vacuole

Question 11

what are the three types of molucule movements ?

Answer 11

• active transport
• osmosis
• diffusion

Question 12

what happens in diffusion ?

Answer 12

• movement of gas and liquid molecules
• high to low concentration
• known as passive movement as no extra energy is required

Question 12

what happens in osmosis ?

Answer 12

• movement of water molecules
• high to low concentration
• known as passive movement as no extra energy is required

Question 12

what happens in active transport ?

Answer 12

• movement of solid molecules
• low to high concentration (agaisnt the concentration gradient)
• known as active movment as energy is required

Question 13

how do you test for startch

Answer 13

• add iodine to the solution
• if it turns black, it’s positive
• if it stays orange, it’s the same

Question 14

how do you test for glucose

Answer 14

• add benedict solution
• heat it
• turns red (lots), orange (medium), green (little), stays blue (nothing)

Question 15

how do you test for lipids

Answer 15

• add distilles water and some ethanol
• will turn cloudy if positive
• stays clear if negative

Question 16

how do you test for protein

Answer 16

• add biuret solution
• goes from blue to purple if positive
• stays blue if negative

Question 17

what are the steps of the core practical: potato osmosis

Answer 17

• get 5 pieces of potatoes (roughly same size)
• measure the initial mass
• pop the potato in the solutions, each solution having different sugar levels
• leave the potatoes for a bit
• measure the new madd then find out the percentage change using: (change in mass g / initial mass) x by 100
• the more sugar, the more mass the potato looses

Question 18

what are the steps of the core practical: PH and enzymes

Answer 18

• add a drop of iodine in each well
• put amylase, pH and startch into a test tube
• add a drop of the solution into each well in 10 second intervals until the colour no longer changes
• repeat it with other pH’s

Question 19

how can you make the core practical: PH and enzymes, more accurate

Answer 19

• repeat the eexperiment with the same pH multiple times

Question 20

what happens in enzyme action

Answer 20

• enzymes and substrates randomly move about in solution
• the complementary substrate collides with its enzyme
• the complex forms and a reaction occurs
• the product(s) are then released of the enzyme

Question 21

state what is meant by the optimum tempurature of an enzyme

Answer 21

the fastest tempurature in which it works at

Question 22

what is the optimum tempurature of an enzyme

Answer 22

37 degrees celcius (woah thats kinda high)

Question 23

how does the denaturing of an enzyme happen

Answer 23

• enzymes are held together by bonds
• high tempuratures or extremes of pH can disrupt or break the active site
• this is IRREVERSIBLE (( very very devastating :,( ))