Warning: Illegal string offset 'html' in /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php on line 909

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 114

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 127

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 136

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 137

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 141
URGENT BIOLOGY HELP NEEDED - HSN forum

Jump to content


URGENT BIOLOGY HELP NEEDED


3 replies to this topic

#1 james1

    Top of the Class

  • Members
  • PipPipPipPipPip
  • 334 posts

Posted 18 May 2004 - 09:23 PM

Could someone urgently please provide me with the following multiple choice answers from past papers:

2002 (Q's 12,13,17)

2002 Winter (Q's 14,16,22)

Thanks.

#2 james1

    Top of the Class

  • Members
  • PipPipPipPipPip
  • 334 posts

Posted 18 May 2004 - 10:02 PM

Anyone?

#3 james1

    Top of the Class

  • Members
  • PipPipPipPipPip
  • 334 posts

Posted 19 May 2004 - 07:37 AM

Please help this morning. Sorry about short notice!

If you have time please explain answers.

A hybrid is created from a cross between two closely relate plants whose chromosome numbers are 14 and 28.
Which of the following statements is true for the offspring of this cross?
a)Their cells contain 21 chromosomes and are fertile.
b)Their cells contain 21 chromosomes and are sterile.
c)Their cells contain 42 chromosomes and are fertile.
d)Their cells contain 42 chromosomes and are sterile.

cabbage and raddish each have a diploid number of 18. these plants can be crossed to produce a hybrid. which of the following is correct:
A) the hybrid contains 9 pairs of homologous chromosomes
B) the chromosomes in the hybrid cannot pair during meiosis
C) the hybrid can produce gametes with a haploid no of 9
D) the hybrid can interbreed successfully with either parents

A plant which has a diploid chromosome number of 26 was discovered in the vicinity of two different species of the genus which proved to be its parents. The gametes from one parent plant contained 7 chromosomes. What would be the diploid chromosome number of the other plant?
A) 12
B) 20
C) 33
D) 40

#4 Vixus

    Top of the Class

  • Members
  • PipPipPipPipPip
  • 260 posts
  • Gender:Male

Posted 10 May 2005 - 06:53 PM

A hybrid is created from a cross between two closely related plants whose chromosome numbers are 14 and 28.
Which of the following statements is true for the offspring of this cross?
a)Their cells contain 21 chromosomes and are fertile.
b)Their cells contain 21 chromosomes and are sterile.
c)Their cells contain 42 chromosomes and are fertile.
d)Their cells contain 42 chromosomes and are sterile.

Why? Because this is hybridisation. Remember that the haploid numbers of 14 and 28 are 7 and 14 (the chromosomes in each gamete of the plants).
7+14 = 21 <-- Chromosome number of new plant.
The new plant is sterile however, because the chromosomes cannot form homologous pairs during meiosis.



Cabbage and radish each have a diploid number of 18. these plants can be crossed to produce a hybrid. which of the following is correct:
A) the hybrid contains 9 pairs of homologous chromosomes
B) the chromosomes in the hybrid cannot pair during meiosis
C) the hybrid can produce gametes with a haploid no of 9
D) the hybrid can interbreed successfully with either parents

Why? Seeing as each chromosome from the 'pair' are from different species and thus the squence of genes will be different, they cannot homologously form pairs during meiosis.


A plant which has a diploid chromosome number of 26 was discovered in the vicinity of two different species of the genus which proved to be its parents. The gametes from one parent plant contained 7 chromosomes. What would be the diploid chromosome number of the other plant?
A) 12
B) 20
C) 33
D) 40

Why? Gametes from parent = 7 chromosomes.
7x2=14 chromosomes diploid. 26-14 = 12.






1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users