4 (a) Figure 4 shows the structures in a leaf - Edexcel - GCSE Biology - Question 4 - 2019 - Paper 1
Question 4
4 (a) Figure 4 shows the structures in a leaf.
Explain how structure Z is involved in defence against pathogens. (2)
(b) Chemicals can be extracted from plants. So... show full transcript
Worked Solution & Example Answer:4 (a) Figure 4 shows the structures in a leaf - Edexcel - GCSE Biology - Question 4 - 2019 - Paper 1
Step 1
Explain how structure Z is involved in defence against pathogens.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Structure Z, represented as a waxy cuticle, acts as a physical barrier that prevents pathogens from entering the plant. This waterproof surface helps to safeguard the inner tissues from pathogenic organisms and fungal infections.
Step 2
What is being shown in Figure 5?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Aseptic technique
Step 3
Explain why the scientist worked near to a Bunsen burner.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The scientist worked near a Bunsen burner to create an aseptic environment. The flame helps to sterilize the air and eliminate airborne microorganisms, thus reducing the risk of contamination of the nutrient agar plate.
Step 4
Calculate the area of the zone of inhibition for chemical A.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To calculate the area of the zone of inhibition for chemical A, use the formula for the area of a circle:
Area=πr2
Substituting for chemical A:
Area=3.14×(12extmm)2=3.14×144=452.16extmm2
Thus, the area of the zone of inhibition for chemical A is 452.16 mm².
Step 5
Give two variables the scientist needed to control to make this conclusion valid.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Temperature of the environment in which the experiment is conducted.
Concentration of the chemicals used in the filter paper discs.
Step 6
Explain one advantage of producing these genetically modified crop plants.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
One advantage of geneticallymodified crop plants is that they can be engineered to produce toxic chemicals that deter pests and reduce the need for chemical pesticides. This can lead to lower agricultural costs and a more sustainable farming practice.
