科研人员得到黄体隐性突变体果蝇(M),M的体重比野生型(黑体)小。为研究是否可将黄体基因作为筛选体重性状的标记基因,进行图1所示杂交实验。请分析回答: (1) F1雌蝇的表现型为_________,将F1雌蝇与野生型雄蝇杂交,在全部F2个体中,黑体:黄体的比例约为__________,F2雄蝇中II 号个体的X染色体上携带黄体基因片段,其原因是F1雌蝇在形成配子时_________。(2) 科研人员选择F2中的黄体雄蝇,进行图2所示杂交实验。 ①与步骤3的黄体雄蝇相比 “Congratulations, Mr. Jones, it’s a girl.”
Fatherhood is going to have a different meaning and
bring forth a different answer from every
Man who hears these words. Some feel proud when
they receive the news, while others worry, wondering whether they will be good
fathers.Although there are some men who like children
and may have had considerable experience with them,
others do not particularly care for children and spend little time with them.Many
fathers and mothers have been planning and looking forward to children for some
time.For other couples, pregnancy was an
accident that both husband and wife have accepted willingly or unwillingly.
Whatever the
reaction to the birth of a child, it is obvious that the shift from the role of
husband to that of father is a difficult task.Yet,
unfortunately, few attempts have been made to educate fathers
in this remobilization process.Although numerous books have been written about
American mothers, only recently has literature focused on the
role of a father.
It is argued by
some writers that the transition to the father‘s role,
although difficult, is not nearly as great as the transition the
wife must make to the mother‘s role.The mother‘s role
seems to require complete transformation in daily routine and highly innovative
adaptation; on the other hand, the fathers role is less demanding and
immediate.However, even though we
mentioned the fact that growing number of women are working outside the home,
the father is still thought by many as the breadwinner in the household.
1.According
to the author,being a father_________.
A.brings
a feeling of excitement to some men
B.has
a different meaning for those who have daughters
C.makes
some men feel proud and others uneasy
D.means
nothing but more responsibilities
2.It
is stated in the passage that__________.
A.some
parents are not prepared to have a child
B.young
couples do not like children at all
C.do
not have much time to take care of their children
D.many
parents look forward to having a boy as their first child
3.The
transition to the mother‘s role requires that the wife__________.
A.change
her lifestyle in a highly innovative way
B.make
a complete change in her everyday life to deal with the new situation
C.stay
at home to take care of the baby
D.help
her husband in his remobilization process
4.Some writers argue that
with respect to the change of roles, fathers,
compared with mothers, ___________.
A.have
to shoulder more burdens
B.have
to make more difficult adaptations
C.have
an easier job to do
D.can
usually do a better job