What is the phenotype of the F1 rats?
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All black fur.
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What is the phenotype of the F1 rats?
All black fur.
Provide the gametes for the F2 rat with black fur.
B and b.
What is the chromosome combination for females?
XX.
What do the testes produce in XY embryos?
Male sex hormones.
What do the ovaries produce in XX embryos?
Female sex hormones.
What are the possible blood groups of the second child?
A, B, AB, or O.
What is the result of Mendel's monohybrid cross for stem length?
The F2 generation consists of both tall and short plants in a ratio of 3:1.
What is the law of independent assortment (Mendel’s second law)?
It states that the separation of alleles of one gene is independent of the separation of alleles of other genes during gamete formation.
What is the position of a gene on a chromosome called?
Gene locus (plural: loci).
Who discovered the structure of DNA using X-ray diffraction?
Rosalind Franklin and Maurice Wilkins.
What technique did Rosalind Franklin and Maurice Wilkins use to study the structure of DNA?
X-ray diffraction.
What did Mendel study at first in his experiments?
The inheritance of one pair of contrasting characters of pea plants at a time.
What is a test cross in genetics?
Involves crossing an organism of unknown genotype with a homozygous recessive organism.
What is dihybrid inheritance?
The simultaneous inheritance of two characteristics controlled by two different genes.
What holds the two strands of DNA together and stabilizes the helical structure?
Hydrogen bonds between the bases.
What did Mendel study in his dihybrid inheritance experiment with pea plants?
The inheritance of seed shape and seed color.
How does the sex of a baby depend on the fertilizing sperm?
If an X-bearing sperm fertilizes the ovum, the resulting zygote will develop into a female, while if a Y-bearing sperm fertilizes the ovum, the resulting zygote will develop into a male.
What is the term for an individual with two different alleles for a gene?
Heterozygote.
What are the phenotypes of the offspring in the given scenario?
Long wings and vestigial wings.
What is DNA?
Deoxyribonucleic acid (DNA) is the chemical that stores the genetic information in a cell.
How are genes passed from one generation to the next?
Genes are passed from one generation to the next through the transmission of genetic material from parent to offspring during reproduction.
Where is DNA found inside the onion cell?
Inside the nucleus.
What did Mendel study in his breeding experiments?
How characteristics are passed from one generation to the next.
How are alleles represented in the given scenario?
Capital letter for dominant allele (N) and small letter for recessive allele (n).
What are the phenotypes and genotypes of the parent with long wings?
Phenotype: long wings, Genotype: Nn.
What are the possible alleles carried by the gametes of the parents?
N and n.
What are chromosomes made up of?
DNA and proteins.
What does a DNA molecule consist of?
Two polynucleotide chains that run in opposite directions and are twisted together to form a double helix.
What do pure-breeding plants always produce when self-pollinated?
Offspring with the same character.
What is a gene?
A gene is a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
What is a gene?
A short length of DNA in a chromosome that provides the genetic code for a polypeptide.
What components need to be broken down to free the DNA from onion cells?
Cell wall, cell membrane, and nuclear membrane.
What is an example of a characteristic controlled by a single gene in fruit flies?
The length of wings, which is controlled by a pair of alleles.
In maize, which allele for grain color is dominant?
The allele for dark-colored grains is dominant to the allele for light-colored grains.
What does the I A allele lead to?
The production of antigen A.
What is dihybrid inheritance?
The simultaneous inheritance of two characteristics controlled by two different genes.
What happens when genes are close together on the same chromosome?
They tend to stay together during meiosis and enter the same gamete, inheriting as a unit, known as linkage.
What is genetics?
The study of heredity and variations in organisms.
What did the F1 generation of seeds produced in Mendel's experiment exhibit?
Round and yellow characteristics.
What determines whether a zygote will develop into a female or a male?
The presence of two X chromosomes (XX) results in a female, while the presence of an X and a Y chromosome (XY) results in a male.
What are genes?
Characteristics passed from parents to offspring through genes.
What are the traits controlled by genes located on the sex chromosomes known as?
Sex-linked traits.
What does a DNA molecule consist of?
Two polynucleotide chains (i.e. two DNA strands).
What is the genotype of the F2 rat with black fur?
Heterozygous (Bb).
In fruit flies, what is the dominant character for wing length?
Long wings.
What do the alleles R and r represent in the dihybrid crosses?
R represents the allele for round seeds and r represents the allele for wrinkled seeds.
What is the result of a cross between a man with normal color vision and his wife who is a carrier of red-green color blindness?
The offspring will have a ratio of different genotypes and phenotypes related to color vision.
What is the chromosome combination for males?
XY.
What are the two types of antibodies that may be present in the plasma based on blood group?
Anti-A and anti-B.
Where is genetic information stored in DNA?
In the sequence of the nucleotide bases.
Who was the first person to study inheritance in a scientific way?
Gregor Mendel (1822–1884).
What makes the DNA extracted in this practical visible to the naked eye?
Impurities such as proteins.
What happens to homologous chromosomes during gamete formation?
They separate from each other.
What is the law that states each gamete receives one allele from each pair?
The law of segregation, or Mendel’s first law of inheritance.
What is the purpose of adding ice-cold ethanol to the filtrate?
To form a layer on top of the filtrate and extract DNA.
What is the probability of having a boy or a girl at each birth?
There is an equal chance of having a boy or a girl at each birth.
What is the term for the allele whose expression is masked by another allele?
Recessive allele.
Where are most of the sex-linked genes located in humans?
On the X chromosome.
What is a gene?
A short length of DNA in a chromosome that determines the body characteristics of an organism by controlling what proteins are made.
What does it mean if an individual has the same allele in both members of a chromosome pair?
The individual is said to be homozygous for the gene.
What is the result that confirms a pea plant with green pods is a homozygote?
Cross it with another pea plant with yellow pods. All the F1 offspring have green pods.
What enables DNA to replicate every time a cell divides?
Complementary base pairing.
What is a dihybrid cross?
A cross between two parents differing in two characteristics.
What does it mean when an individual is homozygous for a gene?
Both chromosomes carry the same allele of the gene at this locus.
What does it mean when an individual is heterozygous for a gene?
Each chromosome carries a different allele of the gene at this locus.
What are variations in genetics?
Differences in a particular characteristic among individuals of a species.
What is Mendel's law of independent assortment?
During gamete formation, alleles of one gene separate independently of the others, meaning the inheritance of one characteristic is independent of the inheritance of another.
What character did all plants in the F1 generation exhibit?
Tall.
What does 'R' represent in the genotypes concerning color vision?
The dominant allele for normal color vision.
What can genetic diagrams or Punnett squares show in a cross?
How alleles separate during gamete formation and the possible combinations of alleles in the offspring.
What are the genotypes of the female gametes in the dihybrid crosses?
RRYY, RRYy, RrYY, RrYy, RRYy, RRyy, RrYy, Rryy, RrYY, RrYy, rrYY, rrYy, RrYy, Rryy, rrYy, rryy.
What happens when a cell is going to divide?
The chromatin condenses to form a chromosome.
How did Mendel ensure self-pollination in pea plants?
By enclosing the flower in a bag to prevent pollen from another plant from pollinating it.
What is the expected number of offspring with long wings if 100 offspring are produced from two fruit flies heterozygous for long wings?
What are the three possible combinations of alleles when F1 plants self-pollinate?
TT, Tt, and tt.
What do genes determine in an organism?
The body characteristics (or traits) of an organism by controlling what proteins are made.
What is the appearance of pure DNA?
Colourless.
What is heredity?
The passing on of characteristics from one generation of organisms to the next generation.
What did the F2 generation of seeds produced in Mendel's experiment show?
Four different phenotypes: Round and yellow, Round and green, Wrinkled and yellow, Wrinkled and green.
What are genes located on the sex chromosomes known as?
Sex-linked genes.
Who proposed the three-dimensional model for the structure of DNA in 1953?
James Watson and Francis Crick.
Explain why black fur is the dominant phenotype in the F1 rats.
In the heterozygous condition, only the dominant allele will be expressed.
What does 'r' represent in the genotypes concerning color vision?
The recessive allele for red-green color blindness.
What is the ratio of tall plants to short plants in the F2 generation?
3:1.
What do genetic diagrams and Punnett squares give for a particular cross?
Expected results.
What do the alleles Y and y represent in the dihybrid crosses?
Y represents the allele for yellow seeds and y represents the allele for green seeds.
What is the genetic makeup (genotype) of the tall parent and the short parent?
TT and tt respectively.
What are the possible genotypes for blood group B?
I B I B, I B i.
What are the genotypes of the couple?
Mother: I A i, Father: I B i.
Apart from genes, what other factors can affect our body characteristics?
Apart from genes, environmental factors and lifestyle choices can also affect our body characteristics.
What type of bonds join the sugar and phosphate groups in DNA?
Covalent bonds.
What are the possible outcomes of a test cross between a tall pea plant and a short pea plant?
If the tall plant is homozygous dominant, all of the F1 offspring will be tall. If the tall plant is heterozygous, half the number of the F1 offspring will be tall and half will be short with a phenotypic ratio of 1:1.
What is the difference in the process of meiosis between the female ovary and the male testes?
All ova receive an X chromosome, while half of the sperms receive an X chromosome and the other half receive a Y chromosome.
What safety precautions should be taken when handling hot water in this practical?
Wear safety goggles and heat-resistant gloves.
What causes albinism in humans?
Albinism is caused by a recessive allele, resulting in a lack of pigments that give color to the skin, hair, and eyes.
What is the term for the allele that masks the expression of another allele?
Dominant allele.
How can the genotypes of the offspring be worked out?
By adding lines for all possible combinations of gametes.
How are the two polynucleotide chains in a DNA molecule held together?
By hydrogen bonds between the bases. A always pairs with T, and G with C.
What blood group does not have antigen A or B on their red blood cells and is called the universal donor?
Blood group O.
Explain why the F2 rat with black fur is heterozygous.
Because some of the offspring have brown fur.
What are the four nitrogenous bases attached to the sugar of each nucleotide?
Adenine (A), thymine (T), guanine (G), and cytosine (C).
What is the phenotypic ratio of the offspring from the test cross?
1:1 black fur to brown fur.
What does the structure of DNA wrap around to form a chromosome?
Proteins.
What does the law of segregation state?
Alleles of a gene separate from each other during meiosis.
What is the name of the ratio resulting from Mendel's monohybrid cross?
Monohybrid ratio.
What are the possible genotypes of an organism showing a dominant character?
Homozygous dominant (TT) or heterozygous (Tt).
What are alleles?
Two or more alternative forms of a gene that lie at the same gene locus on a pair of homologous chromosomes.
What is the process that makes an exact copy of DNA every time a cell divides?
DNA replication.
What determines whether a person has five or six fingers on each hand in humans?
It is controlled by a pair of alleles, with the allele for six-fingered hands being dominant.
What did Watson, Crick, and Wilkins contribute to the discovery of the DNA structure?
Watson and Crick proposed the double helix model for DNA by combining the results of X-ray diffraction analysis with the data obtained by Chargaff. Wilkins also contributed to the study of the DNA structure.
What is the appearance of the DNA when it is wound around the wooden stick?
Observe and record the appearance of the DNA as the stick is drawn out of the tube.
What is the difference in size and gene content between the X and Y chromosomes?
The X chromosome is much larger and carries more genes than the Y chromosome.
Where is DNA usually found?
In the nucleus of a cell.
What is chromatin?
DNA molecule that wraps around special proteins and coils up to form chromatin.
What is the backbone of the DNA molecule made up of?
Sugar (deoxyribose) and phosphate groups of nucleotides.
What are the two types of sex chromosomes?
X chromosome and Y chromosome.
Which DNA base pairs correctly represent the pairing?
A always pairs with T, and G with C.
What did Mendel observe in the F2 generation of his breeding experiments?
The character that had disappeared in the F1 generation showed up again, and there was an approximately 3:1 ratio of the two characters in the offspring.
What is a test cross in genetics?
A test cross is a cross between an organism showing a dominant character and a homozygous recessive individual to determine the genotype of the dominant organism.
Why did Mendel choose to conduct breeding experiments on garden pea plants?
Because they had easily observable characteristics, grew fast, and were easy to handle.
What is monohybrid inheritance?
The inheritance of one pair of contrasting characters (two different expressions of a characteristic) controlled by a single gene.
What did Mendel cross-pollinate in one of his experiments?
Pure-breeding tall plants with pure-breeding short plants.
What were the plants produced known as in Mendel's experiment?
The first filial generation (F1 generation).
Based on the results of the cross, which fur color is dominant?
Black fur.
What is the ratio of phenotypes in the F2 generation resulting from random fertilization of gametes from the F1 generation?
9:3:3:1, known as the dihybrid ratio.
What is the F2 generation?
The second filial generation resulting from the self-pollination of F1 plants.
What does the phenotypic ratio of 3:1 mean in terms of percentage?
75% will have long wings, and 25% will have vestigial wings.
What is the genotype of the pure-breeding short parent in terms of alleles?
tt.
What difficulty do people with red-green colour blindness experience?
Difficulty in distinguishing red colour and green colour.
What did Mendel's monohybrid crosses on pea plants reveal?
The inheritance patterns of specific characteristics such as stem length, flower color, pod shape, and seed color.
What does it mean for alleles I A and I B to be codominant?
Both alleles can be expressed in a heterozygote.
What did Erwin Chargaff discover about the DNA of different species of organisms?
The DNA of different species of organisms differed in the proportions of bases. The percentage of adenine (A) was very similar to the percentage of thymine (T), and the same applied to guanine (G) and cytosine (C).
What are Mendel's laws of inheritance?
Law of segregation and law of independent assortment.
What does 'X' represent in the genotypes concerning color vision?
The X chromosome.
What is the F1 generation?
The first filial generation resulting from the cross of two parental plants.
What are the genotypes of the male gametes in the dihybrid crosses?
RRYY, RRYy, RrYY, RrYy, RRYy, RRyy, RrYy, Rryy, RrYY, RrYy, rrYY, rrYy, RrYy, Rryy, rrYy, rryy.
What is the genotype of the pure-breeding tall parent in terms of alleles?
TT.
What causes red-green colour blindness?
A recessive allele on the X chromosome.
What does it mean for an organism to be homozygous?
Having two identical alleles for a particular gene.
What did Mendel observe in the F1 generation of his breeding experiments?
Only one of the two contrasting characters of the parent plants was observed.
What does the i allele lead to?
It does not lead to the production of any antigen.
What personal attributes helped Watson and Crick build the DNA model?
Their creativity, collaboration, and ability to combine different scientific findings.
What is the genotypic ratio of the offspring (NN:Nn:nn)?
1:2:1.
What is the phenotypic ratio of the offspring for long wings to vestigial wings?
3:1.
What type of genetic disorder is red-green colour blindness?
X-linked.
How many pairs of chromosomes do human body cells contain?
23 pairs.
What does it mean if the two alleles in a chromosome pair are different?
The individual is said to be heterozygous for the gene.
What gene on the Y chromosome determines the sex of a human embryo?
SRY (sex-determining region Y).
What is the purpose of constructing a Punnett square?
To predict the possible combinations of gametes and the phenotypes of the offspring.
What does the I B allele lead to?
The production of antigen B.
What blood group can receive blood from any other blood group and is called the universal recipient?
Blood group AB.
What are the two strands of DNA twisted together to form?
A double helix.
What happens after fertilization in Mendel's cross-pollination process?
The carpel develops into a pod with seeds inside.
Why is red-green color blindness more common in males than in females?
Males have only one X chromosome, and if their X chromosome carries the recessive allele, they will be red-green color-blind.
How do the bases on one DNA strand pair up with those on the other strand?
Through hydrogen bonds, with A always pairing with T, and G pairing with C.
If a DNA molecule contains 20% cytosine (C), what is the percentage of adenine (A) in this DNA molecule?
30%.
What are the four main blood groups in humans?
A, B, AB, and O.
What are the possible genotypes for blood group AB?
I A I B.
What steps did Mendel follow to cross-pollinate the plants?
Remove stamens from immature flower, transfer pollen grains from the stamens of a flower of another variety onto the stigma, collect the seeds and sow them.
What is the term used for a female who carries the recessive allele but does not express it?
Carrier.
What is a monohybrid cross?
A genetic cross between two parent plants that differ in only one single characteristic.
What may not match the expected results in genetic crosses?
The results actually observed.
What does the DNA structure resemble?
A ladder, with alternating sugar and phosphate groups forming the sides and pairs of bases representing the rungs.
What are the 'heredity factors' proposed by Mendel known as in modern genetic language?
Alleles of the same gene.
What are the possible genotypes for blood group A?
I A I A, I A i.
What happens if a recipient receives blood from a donor of an incompatible blood group?
The antibodies present in the recipient’s plasma will combine with the antigens on the donor’s red blood cells, causing the red blood cells to clump together.
What does it mean for the allele i to be recessive?
It can only be expressed in a homozygote.
What did Mendel propose about inherited characteristics?
He proposed that inherited characteristics were controlled by pairs of 'heredity factors' passed on from parents to offspring.
How is a person's blood group determined?
By the presence or absence of antigens A and B on the surface of red blood cells.
What are the possible genotypes for blood group O?
ii.
How many alleles control the production of antigens on red blood cells?
Three alleles (multiple alleles).
