Unit 1 Revision: Cloze Exercise 4.
Cell Function & Inheritance
Chromosomes & Meiosis
WORDBANK: ASSORTMENT, AUTOSOMES, CHROMOSOMES, COMPLEMENT,
CROSSING OVER, DIPLOID, DIVISION, DNA, GAMETES, GENE, GENERATION,
GENOTYPE, HAPLOID, HOMOLOGOUS, MEIOSIS, NUCLEAR, REPLICATION,
SEX, UNPAIRED, VARIATION.
1. A
is a unit of heredity, which controls a characteristic.
It consists of a region of
on a chromosome.
2. A species chromosome
is the characteristic number
of chromosomes that it possesses (46 in human). These
can be arranged into
gene for gene.
pairs which match one another
3. In a human, one pair of chromosomes determines the
of the individual and are called the sex chromosomes. The other 22 pairs
are called
.
4. A cell containing 46 chromosomes as 23 pairs is
containing 23
: a cell
chromosomes is haploid.
5.
is the process by which the nucleus of a diploid
gamete mother cell divides into four, resulting in the formation of
four
.
6. Prior to nuclear
, the amount of chromosomal material
doubles by DNA undergoing
exactly.
and reproducing itself
7. DNA replication allows genetic information to be passed on from cell to
cell and from generation to
8. Meiosis involves two consecutive
.
divisions and
produces
reproduction.
gametes in preparation for sexual
9. During meiosis, new combinations of existing alleles arise by
independent
chromosomes.
and
between homologous
10. The meeting of two haploid gametes at fertilisation allows mixing of
part of one person's
with that of another. By producing
diploid individual who are genetically different from their parents, this
process produces
species.
amongst the members of the human
ANSWERS: Unit 1 Revision: Cloze Exercise 4.
Cell Function & Inheritance
Chromosomes & Meiosis
1. A gene is a unit of heredity, which controls a characteristic. It consists of a region
of DNA on a chromosome.
2. A species chromosome complement is the characteristic number of chromosomes
that it possesses (46 in human). These chromosomes can be arranged
into homologous pairs which match one another gene for gene.
3. In a human, one pair of chromosomes determines the sex of the individual and are
called the sex chromosomes. The other 22 pairs are called autosomes.
4. A cell containing 46 chromosomes as 23 pairs is diploid: a cell containing
23 unpaired chromosomes is haploid.
5. Meiosis is the process by which the nucleus of a diploid gamete mother cell divides
into four, resulting in the formation of four gametes.
6. Prior to nuclear division, the amount of chromosomal material doubles by DNA
undergoing replication and reproducing itself exactly.
7. DNA replication allows genetic information to be passed on from cell to cell and from
generation to generation.
8. Meiosis involves two consecutive nuclear divisions and produces haploid gametes in
preparation for sexual reproduction.
9. During meiosis, new combinations of existing alleles arise by
independent assortment and crossing over between homologous chromosomes.
10. The meeting of two haploid gametes at fertilisation allows mixing of part of one
person's genotype with that of another. By producing diploid individual who are
genetically different from their parents, this process produces variation amongst the
members of the human species.