AS Level Biology A H020/02 Depth in
biology Tuesday 6 June 2017 - Afternoon
QUESTIONS AND ANSWERS
1. Alveoli are positioned in the lungs of mammals. Explain how alveoli are tailored for green
gas exchange. - ANSWER-Thin partitions: Squamous epithelium- flat for a brief
diffusion pathway
correct blood supply- creates steep concentration gradient
Elastic fibers- stretch and balk- keep concentration gradient
Large floor- massive numbers of alveoli
Another stage of meiosis is metaphase 1.
2. Explain how the employer of homologous chromosomes at some stage in metaphase 1
will increase genetic variation - ANSWER-independent collection
chromosomes line up on the Centre of the equator
every chromosome of the homologous pair is genetically special
3. Based handiest on your observations of Fig.1.2, state reasons on your answer in (b)(i) -
ANSWER-chromosomes condense
chromosomes nonetheless now not aligned at the equator
4. Bony fish and insects have specific gasoline exchange systems. Both can be determined
by using dissection.
(a) Describe how you'll perform the dissection to show most element of either fuel trade
machine. - ANSWER-reduce open the exoskeleton
5. Cell B in Fig. 1.1 turned into located the use of an electron microscope. Give one piece
of proof from Fig. 1.1 that helps this - ANSWER-organelles can be seen in extra
element
6. Describe how the trachea of a mammal isn't the same as the trachea shown in Fig 3 -
ANSWER-Mammals have just one trachea
Insects have multiple
Mammal trachea is longer
Insects trachae shorter
Mammal trachea larger diameter
insects smaller diameter
7. Give one manner that an image produced by means of a laser scanning confocal
microscope differs from that produced by an electron microscope - ANSWER-laser
scanning confocal microscope has decrease decision
biology Tuesday 6 June 2017 - Afternoon
QUESTIONS AND ANSWERS
1. Alveoli are positioned in the lungs of mammals. Explain how alveoli are tailored for green
gas exchange. - ANSWER-Thin partitions: Squamous epithelium- flat for a brief
diffusion pathway
correct blood supply- creates steep concentration gradient
Elastic fibers- stretch and balk- keep concentration gradient
Large floor- massive numbers of alveoli
Another stage of meiosis is metaphase 1.
2. Explain how the employer of homologous chromosomes at some stage in metaphase 1
will increase genetic variation - ANSWER-independent collection
chromosomes line up on the Centre of the equator
every chromosome of the homologous pair is genetically special
3. Based handiest on your observations of Fig.1.2, state reasons on your answer in (b)(i) -
ANSWER-chromosomes condense
chromosomes nonetheless now not aligned at the equator
4. Bony fish and insects have specific gasoline exchange systems. Both can be determined
by using dissection.
(a) Describe how you'll perform the dissection to show most element of either fuel trade
machine. - ANSWER-reduce open the exoskeleton
5. Cell B in Fig. 1.1 turned into located the use of an electron microscope. Give one piece
of proof from Fig. 1.1 that helps this - ANSWER-organelles can be seen in extra
element
6. Describe how the trachea of a mammal isn't the same as the trachea shown in Fig 3 -
ANSWER-Mammals have just one trachea
Insects have multiple
Mammal trachea is longer
Insects trachae shorter
Mammal trachea larger diameter
insects smaller diameter
7. Give one manner that an image produced by means of a laser scanning confocal
microscope differs from that produced by an electron microscope - ANSWER-laser
scanning confocal microscope has decrease decision
