pp 42 2019 Flashcards
State 5 features that are common to all arthropods.
exoskeleton
segmented, limbs
pairs of, limbs
segmented (body);
bilateral body symmetry ;
state 3 features of arachnids
4 pairs of legs
fused head and thorax / cephalothorax
(pedi)palps
Explain the term adaptive feature [4]
inherited feature controlled by gene(s) / allele(s)
functional feature ;
increase chances of survival
increases chance of reproducing (to leave offspring)
DNA can be extracted from the webs of spiders. This DNA can be used to identify the species of spider that made the web, and the species of prey caught in the web.
Explain how DNA extracted from spider webs can be used to identify different species. [4]
identification can be done using: base, sequences in DNA / genes
each species, has unique genes ;
compared with reference DNA of known species ;
if it matche with DNA from known species then DNA is from that species OR closely related species
Many species of spider are thought to be endangered.
State three reasons why animal species such as spiders become endangered. [7]
hunting / collecting / AW ;
pesticides
loss of habitat
disease
increase in predator(s) ;
climate change
not enough food
Draw a circle around one vascular bundle on Fig. 2.1. Label the xylem in the vascular bundle with the letter X.
any shape drawn that includes one whole vascular bundle including all of the xylem and phloem with or without sclerenchyma ; label line from X to xylem in any of the vascular bundles ;
Fig. 2.1. Explain how the cells in area Y are able to support the stem so that it stays upright. [5]
cells, contain (much) water / have high water potential ;
water absorbed, by osmosis / down water potential gradient ;
cells, are turgid / have a turgor pressure ;
cell contents / vacuole / cell membrane, pushes out (against cell wall) ;
cell wall does not stretch
Table 2.1Describe and explain the effect of removing the phloem on the translocation of sucrose in plants Q, R, S and T. 6
Q sucrose is in shoot and root ;
T no, sucrose in shoot or root ;
R sucrose in root only
S sucrose / 13C, in shoot only
no transport of where phloem is removed
phloem transports (sucrose) in both directions
what do cells in the lining of the stomach secrete
gastric juice
what does gastric juice contain [2]
hydrochloric acid and pepsin.
State roles of hydrochloric acid in the stomach. [3]
provides suitable pH for enzyme action ;
activates enzyme / pepsin ;
kills pathogens
Describe the function of pepsin.
chemically digests protein to amino acids ;
Define the term assimilation [2]
movement of digested food molecules into cells
food molecules become part of cells
There are stem cells in the epithelial tissue that forms the lining of the stomach. Explain why these stem cells are necessary [5]
stem cells divide by mitosis ;
form specialised cells in stomach ;
to replace cells (in the lining of stomach) ;
cells are worn away from the surface of the stomach ;
for repair of any damage to tissues ;
The epithelial cells of the small intestine have many microvilli. State the role of the microvilli [2]
increase surface area ;
for absorption of nutrients
Fig. 3.1 Calculate the percentage increase in the average number of bacteria attached to epithelial cells from 45 minutes to 75 minutes.
54(%)
one mark for correct readings (78 minutes and 120 minutes)
one mark for correct calculation
one mark for whole number correctly rounded
Explain how the human gas exchange system is protected against pathogens. [6]
mechanical / chemical, barriers
nasal hairs trap pathogens
mucus traps pathogens
cilia move mucus upwards ;
coughing / sneezing / swallowing ;
phagocytes / phagocytosis
Tuberculosis (TB) is a transmissible disease caused by a bacterial pathogen. The spread of this disease can be controlled by vaccination.
Explain how vaccination provides a defence against transmissible diseases [6]
introduces harmless form of pathogen
stimulates an immune response ;
lymphocytes produce antibodies ;
(lymphocytes develop into) memory cells ;
memory cells, give long-term immunity / can produce antibodies (at a later time) ;
respond quickly when an infection (of the same pathogen) occurs / before symptoms occur ;