The Physical Basis of Heredity Practice Test

Review the following concepts if needed:

The Physical Basis of Heredity Practice Test

Matching Questions

Choose the one best match for each organelle (in the left column) with its function or description (in the right column). No organelle has more than one match.

Cell Organelle	Function or Description
1. Mitochondria	A. Establishes polar region
2. Centrioles	B. May contain a photosynthetic system
3. Chromosome	C. Site of protein synthesis
4. Nucleus	D. Location of genes
5. Nucleolus	E. Organelle involved in protein modification and subcellular localization
6. Ribosome	F. Storage of excess water and other metabolic products
7. Endoplasmic reticulum	G. Site of major ATP synthesis
8. Plastid	H. Organelle containing linear chromosomes
9. Golgi body	I. Cytoplasmic membrane network
10. Vacuole	J. RNA-rich region in nucleus

Vocabulary Questions

For each of the following definitions, give the appropriate term. Terms are single words unless indicated otherwise.

Any chromosome other than a sex chromosome.
Site on a chromosome to which spindle fibers attach.
Adjective applicable to a chromosome with arms of about equal length.
Adjective referring to the number of chromosomes in a gamete
Specialized cell division process consisting of a reductional and an equational division.
Division of the cytoplasm.
The first phase of mitosis.
The cytological structure on paired chromosomes with which genetic exchange (crossing over) is correlated.
Chromosomes that contain enough similar genetic material to pair in meiosis.
The period between mitotic division cycles.

Multiple-Choice Questions

Choose the single most appropriate answer.

An organelle present in animal cells but missing from plant cells is (a) a nucleolus (b) a centriole (c) a vacuole (d) a mitochondrion (e) more than one of the above
During the meiosis I division, chromosomes divide (a) equationally (b) reductionally.
Humans normally have 46 chromosomes in skin cells. How many autosomes would be expected in a kidney cell? (a) 46 (b) 23 (c) 47 (d) 44 (e) none of the above
During mitosis, synapsis occurs in the phase called (a) telophase (b) anaphase (c) prophase (d) metaphase (e) none of the above
If the genetic endowments of two nuclei that unite to produce the plant zygote are labeled A and B, and the other product of fertilization within that same embryo sac is labeled ABB, then the tube nucleus that was in the pollen tube that delivered the fertilizing male gametes must be labeled (a) A (b) AB (c) B (d) BB (e) none of the above
A locus is best defined as (a) an alternative form of a gene (b) the position of a gene on a chromosome (c) a cellular structure composed of DNA and protein (d) a fertilized egg (e) the place on a chromosome where spindle fibers attach
The different forms of a gene are called (a) gametes (b) loci (c) homologues (d) alleles (e) ribosomes
Which of the following cells is normally diploid? (a) primary polar body (b) spermatid (c) primary spermatocyte (d) spermatozoan (e) secondary polar body
Upon which two major features of chromosomes does their cytological identification depend? (a) length of chromosome and position of centromere (b) amount of DNA and intensity of staining (c) numbers of nucleoli and centromeres (d) number of chromatids and length of arms (e) chromosome thickness and length
In oogenesis, the cell that corresponds to a spermatid is called a(an) (a) ovum (b) egg (c) secondary oocyte (d) oogonium (e) secondary polar body

Problems

There are 40 chromosomes in somatic cells of the house mouse. (a) How many chromosomes does a mouse receive from its father? (b) Howmany autosomes are present in a mouse gamete? (c) Howmany sex chromosomes are there in a mouse ovum? (d) How many autosomes are there in somatic cells of a female?
Identify the mitotic stage represented in each of the following diagrams of isolated cells from an individual with a diploid chromosome complement of one metacentric pair and one acrocentric pair of chromosomes.

The Physical Basis of Heredity Supplementary Problems

Identify the meiotic stage represented in each of the following diagrams of isolated cells from the germ line of an individual with one acrocentric pair and one metacentric pair of chromosomes.

The Physical Basis of Heredity Supplementary Problems

How many different types of gametic chromosomal combinations (paternal vs. maternal) can be formed in the garden pea (2n = 14)? (Hint: See Solved Problem 1.1.)
What animal cells correspond to the three megaspores that degenerate following meiosis in plants?
What plant cell corresponds functionally to the primary spermatocyte?
What is the probability of a sperm cell of a man (n = 23) containing only replicas of the centromeres that were received from his mother? (Hint: See Solved Problem 1.1.)
How many chromosomes of humans (2n = 46) will be found in (a) a secondary spermatocyte, (b) a spermatid, (c) a spermatozoan, (d) a spermatogonium, (e) a primary spermatocyte?
Howmany human egg cells (ova) are produced by (a) an oogonium, (b) a primary oocyte, (c) an ootid, (d) a polar body?
Corn (Zea mays) has a diploid number of 20. How many chromosomes would be expected in (a) a meiotic product (microspore or megaspore), (b) the cell resulting from the first nuclear division (karyokinesis) of a megaspore, (c) a polar nucleus, (d) a sperm nucleus, (e) a microspore mother cell, (f) a leaf cell, (g) a mature embryo sac (after degeneration of nonfunctional nuclei), (h) an egg nucleus, (i) an endosperm cell, (j) a cell of the embryo, (k) a cell of the pericarp, (l) an aleurone cell?
A pollen grain of corn with nuclei labeled A, B, and C fertilized an embryo sac with nuclei labeled D, E, F, G, H, I, J, and K as shown below.

The Physical Basis of Heredity Supplementary Problems

Which of the following five combinations could be found in the embryo: (1) ABC (2) BCI (3) GHC (4) AI (5) CI?
Which of the above five combinations could be found in the aleurone layer of the seed?
Which of the above five combinations could be found in the germinating pollen tube?
Which of the nuclei, if any, in the pollen grain would contain genetically identical sets of chromosomes?
Which of the nuclei in the embryo sac would be chromosomally and genetically equivalent?
Which of the nuclei in these two gametophytes will have no descendants in the mature seed?

A certain plant has eight chromosomes in its root cells: a long metacentric pair, a short metacentric pair, a long telocentric pair, and a short telocentric pair. If this plant fertilizes itself (self-pollination), what proportion of the offspring would be expected to have (a) four pairs of telocentric chromosomes, (b) one telocentric pair and three metacentric pairs of chromosomes, (c) two metacentric and two telocentric pairs of chromosomes?

For Problems 1.17 and 1.18, diagram the designated stages of gametogenesis in a diploid organism that has one pair of metacentric and one pair of acrocentric chromosomes. Label each of the chromatids assuming that the locus of gene A is on the metacentric pair (one of which carries the A allele and its homologue carries the a allele) and that the locus of gene B is on the acrocentric chromosome pair (one of which carries the B allele and its homologue carries the b allele).

Oogenesis: (a) first metaphase; (b) first telophase resulting from part (a); (c) second metaphase resulting from part (b); (d) second telophase resulting from part (c).
Spermatogenesis: (a) anaphase of a dividing spermatogonium, (b) anaphase of a dividing primary spermatocyte, (c) anaphase of a secondary spermatocyte derived from part (b), (d) four sperm cells resulting from part (b).

Answers

Matching

1. G 2. A 3. D 4. H 5. J 6. C 7. I 8. B 9. E 10. F

Vocabulary

autosome
centromere or kinetochore
metacentric
haploid
meiosis
cytokinesis
prophase
chiasma or recombination nodule
homologues
interphase

Multiple-Choice

b
b
d
e (synapsis occurs in meiosis, not mitosis)
a
b
d
c
a
e

Problems

(a) 20 (b) 19 (c)1 (d)38
(a) Metaphase (b) prophase (c) telophase (d) anaphase
(a) 1st anaphase (b) 1st metaphase (c) 2nd prophase or end of 1st telophase (d) 2nd anaphase (e) 1st prophase
2nd telophase (meiotic product) (a) 2⁷ = 128
Polar bodies
Microspore mother cell (microsporocyte); both are diploid cells with the capacity to divide meiotically
(1/2)²³, less than one chance in 8 million
(a) 23 (b) 23 (c) 23 (d) 46 (e) 46
(a) 1 (b) 1 (c) 1 (d) 0
(a) 10 (b) 20 (c) 10 (d) 10 (e) 20 (f) 20 (g) 30 (h) 10 (i) 30 (j) 20 (k) 20 (l) 30
(a) 5 (b) 3 (c) 1 (d) A, B, C (e) D, E, F, G, H, I, J, K (f) A, D, E, F, J, K
(a) 0 (b) 0 (c) All

Only one of several possible solutions is shown for each of Problems 1.17 and 1.18.

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The Physical Basis of Heredity Practice Test