6 Forensics

Question 1

What type of chemical reaction takes place in decomposition?

Answer 1

Hydrolysis

Question 2

Why do we use multiple piles of leaves for an investigation?

Answer 2

To give a range for the independent variable.

Question 3

Describe the role of bacteria from forests that leads to producing carbon dioxide.3

Answer 3

• decomposition of organic matter/ plant material
• bacteria produces hydrolytic enzymes
• respiration produces carbon dioxide

Question 4

Suggest how carbon dioxide is returned to air from the oceans.1

Answer 4

Respiration/decomposition

Question 5

State two features of these bodies that could account for variation in data.

Answer 5

• body size
• fat level
• position of the body

Question 6

Explain why recording rectal temperature is more reliable than measuring skin temperature.2

Answer 6

• more core 37 degrees
• skin temp would be more variable

Question 7

What factor might influence the rate of progress of rigid Morris in a muscle immediately after death?

Answer 7

Presence of drugs in the body

Question 8

Explain why ambient temperature and the core temperature of the body are used to determine the Tod.3

Answer 8

• temperature of the body/core changes with time after death
• core temperature depends upon the ambient temperature
• idea that other post-death changes eg muscle contraction/insect life cycles and degree of decomposition depend on the ambient temperature of the body.

Question 9

Describe the role of decomposers, such as microorganisms, in the carbon cycle.2

Answer 9

• decomposers break down organic material
• decomposer respire/ respiration takes place
• releasing CO2 into atmosphere

Question 10

New data contributing to an understanding of the evolution of grey tree frogs has been investigated.
Suggest two ways in which the results of their investigations can be shared.2

Answer 10

• scientific/peer reviewed journals
• scientific lectures/ conferences
• media reports

Question 11

In addition to body temperature, forensic scientists would look for other evidence of time of death.
Give two other pieces of evidence from a body that allow for an estimation of the time of death.2

Answer 11

• rigor mortis
• degree of decomposition
• forensic entomology

Question 12

Suggest reasons for why

Species of plants cannot be identified from woody (xylem) material using PCR and DNA profiling.2

Answer 12

• xylem/wood is made of dead material it is not living
• No DNA or nucleic acid present

Question 13

Suggest and explain what effect an increase in temperature has on the rate of decompostion on a pile of leaves.4

Answer 13

• increasing temp increases rate of D
• enzymes present so
• increased heat=increased collisions between enzymes and substarte
• increased rate at which bacteria grows due to favoured conditions
• at a certain temp rate slows/stops as too high enzymes will denature

Question 14

Explain why there is a decrease in mass of leaves.4

Answer 14

• bacteria/ decomposers release enzymes for decompostion
• respiration of glucose and CO2 released
• formation of glucos and monomers that are soluble and will dissolve into ground or taken by othner organisms
• water loss from leaves (evaporation)