wrong answers from PPQ (BIO)

outline features of non-self antigens

• stimulates immune response

• usually a protein

• activates phagocytes

• cause production of antibodies

where does active transport of ions and gas exchange occur in plant stem cell?

cell surface membrane

describe how macrophages engulf bacteria

1. by endocytosis

2. antigen on bacteria bind to receptors

3. pinching in of membrane

4. formation of vesicle/phagosome

5. uses ATP

advantages of calculating the number of new cases per 100000 each year in the prevention and control of TB across the world

can make valid comparisons between years/countries

• takes into account the population sizes of different countries

state 2 reasons why it is difficult to reduce the number of cases of TB across the world

1. Mycobacterium / pathogen / TB bacteria, remains dormant in the body ;

2. treatment takes a, long time

3. many people do not complete treatment

4. many people do not have access to treatment

5. drug-resistant / antibiotic resistant, strains of Mycobacterium

6. HIV/AIDS or any other medical condition that increases susceptibility to TB

describe the role of microtubules in mitosis

• forms spindle fibres and attach to centromere

• move sister chromatids to the equator

• spindle fibre shortening in anaphase

describe what happens in cytokenisis

• nuclear envelope reforms around each group of chromosomes

• uncoiling of chromosomes

• nucleolus reforms

• organelles distributed between 2 halves of cell

Identify and explain TWO events that occur during the cell cycle that lead to daughter cells being genetically identical

• semi-conservative replication of DNA

• each chromosomes have 2 identical DNA molecules

• alignment of chromosomes on the equator

• chromatids separate so each cell receives a sister chromatid of each chromosome

• centromere(s) split

why is genetic code described as universal?

each triplet codes for the same amino acid in all living organisms