AS Level Biology A H020/02 Depth in
biology Tuesday 6 June 2017 -
Afternoon
Cell B in Fig. 1.1 was observed using an electron microscope. Give one piece of
evidence from Fig. 1.1 that supports this - Correct Answer organelles can be seen in
more detail
Give one way that an image produced by a laser scanning confocal microscope
differs from that produced by an electron microscope - Correct Answer laser
scanning confocal microscope has lower resolution
Meiosis is a type of nuclear division. Fig. 1.2 shows a photomicrograph of plant cells
undergoing meiosis
identify the stage of meiosis 1 shown in the cell labelled A - Correct Answer
prophase (1)
Based only on your observations of Fig.1.2, state two reasons for your answer in (b)
(i) - Correct Answer chromosomes condense
chromosomes still not aligned at the equator
Another stage of meiosis is metaphase 1.
Explain how the organization of homologous chromosomes during metaphase 1
increases genetic variation - Correct Answer independent assortment
chromosomes line up at the Centre of the equator
each chromosome of the homologous pair is genetically different
Xylem and phloem are two vascular tissues found in plants.
State one similarity and two differences between the structure of xylem and phloem -
Correct Answer Similarity- both made up of cells joined end to end
Difference- xylem pits- phloem- no pits
Difference- xylem lignified- phloem-not lignified
Difference- xylem no sieve tube elements- phloem sieve tube elements
Bony fish and insects have different gas exchange systems. Both can be observed
by dissection.
(a) Describe how you would carry out the dissection to display maximum detail of
either gas exchange system. - Correct Answer cut open the exoskeleton
trachea, muscle, spiracle, muscle
What is the structure labelled A - Correct Answer Tracheole
Describe how the trachea of a mammal is different from the trachea shown in Fig 3 -
Correct Answer Mammals have just one trachea
Insects have multiple
Mammal trachea is longer
Insects trachae shorter
biology Tuesday 6 June 2017 -
Afternoon
Cell B in Fig. 1.1 was observed using an electron microscope. Give one piece of
evidence from Fig. 1.1 that supports this - Correct Answer organelles can be seen in
more detail
Give one way that an image produced by a laser scanning confocal microscope
differs from that produced by an electron microscope - Correct Answer laser
scanning confocal microscope has lower resolution
Meiosis is a type of nuclear division. Fig. 1.2 shows a photomicrograph of plant cells
undergoing meiosis
identify the stage of meiosis 1 shown in the cell labelled A - Correct Answer
prophase (1)
Based only on your observations of Fig.1.2, state two reasons for your answer in (b)
(i) - Correct Answer chromosomes condense
chromosomes still not aligned at the equator
Another stage of meiosis is metaphase 1.
Explain how the organization of homologous chromosomes during metaphase 1
increases genetic variation - Correct Answer independent assortment
chromosomes line up at the Centre of the equator
each chromosome of the homologous pair is genetically different
Xylem and phloem are two vascular tissues found in plants.
State one similarity and two differences between the structure of xylem and phloem -
Correct Answer Similarity- both made up of cells joined end to end
Difference- xylem pits- phloem- no pits
Difference- xylem lignified- phloem-not lignified
Difference- xylem no sieve tube elements- phloem sieve tube elements
Bony fish and insects have different gas exchange systems. Both can be observed
by dissection.
(a) Describe how you would carry out the dissection to display maximum detail of
either gas exchange system. - Correct Answer cut open the exoskeleton
trachea, muscle, spiracle, muscle
What is the structure labelled A - Correct Answer Tracheole
Describe how the trachea of a mammal is different from the trachea shown in Fig 3 -
Correct Answer Mammals have just one trachea
Insects have multiple
Mammal trachea is longer
Insects trachae shorter
