paper 1 mistakes Flashcards
(12 cards)
define in terms of genetic code:
universal
non-overlapping
(2)
- the same codon always codes for same amino acids
- adjacent codons dont overlap
state 2 roles of helper T cell (2)
- stimulate B cells
- stimulate cytotoxic T cells
- stimulate phagocytes
define species richness and index of diversity (2)
- number of species in a community
- relationship between number of species and number of individuals in each species
explain 2 reasons why glucose uptake by muscle cells increases significantly during exercise (4)
- increased respiration
- to provide more ATP for muscle contraction
- concentration gradient for glucose
- glucose enters by facilitated diffusion
dark stain used on chromosomes binds to some areas more than others making the chromosomes appear striped.
give 2 ways the structure of chromosome differs along its length to result in stain binding more in some areas (2)
- difference in histones
- difference in base sequences
- difference in supercoiling
scientists collected bees using an ethical method.
suggest in each case 1 consideration to make sure their method :
- was ethical
- allowed them to identify accurately the species to which each bee belonged
- must not harm bee
- must allow close examination of bee
formation of an enzyme substrate complex increases the rate of reaction.
explain how (2)
- reduces activation energy
- due to bending bonds
scientists investigated an enzyme which converts ATP to ADP and Pi
in 1 experiment they added a sugar called lyxose and this increased the reaction rate.
lyxose binds to the enzyme. suggest how it increases the rate (3)
- binding alters tertiary structure of enzyme
- active site changes shape
- more ESCs form
scientists are making antivenom. they mix a mixture of venoms from different snakes of same species.
suggest why (2)
- may be different forms of toxin/antigen
- different antibodies are needed
during vaccination each animal in initially injected with small volume of venom then 2 weeks later a larger volume.
use humoral immune response to explain why (3)
- B cells specific to venom reproduce by mitosis
- plasma cells and memory cells form
- 2nd dose produces antibodies in higher concentration and quickly
suggest how heat treatment may damage the phloem (2)
- movement in phloem requires living cells
- heat treatment damages living cells so transport in phloem through plants is only in untreated plants
compare and contrast phospholipids and triglycerides (5)
- both have ester bonds
- both have glycerol
- both have C,H,O but phospholipid has P
- triglyceride non polar but phospholipid has hydrophilic and hydrophobic region
- triglyceride has 3 fatty acids, phospholipid has 2 fatty acids and phosphate head
- both are insoluble in water
