What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci?
a. 3:1
b. 9:3:3:1
c. 1:1:1:1
d. 1:2:1
e. 9:4:2:1
Answer:
c. 1:1:1:1
Explanation:
When a heterozygous individual for two genes is test crossed with a double homozygous recessive individual, the progeny is obtained in 1:1:1:1 phenotypic ratio. This occurs as the heterozygous dominant individual forms four types of gametes in 1:1:1:1 ratio while the homozygous recessive individual would form only one type of gamete having one recessive allele for each gene.
For example, a test cross between TtRr (tall and red) and ttrr (short and white) would produce a progeny in following ratio=
1 tall, red: 1 tall, white: 1 short, red: 1 short, white
Here, T= tall, t= short, R= red, r= white
Answer: The correct answer is Mitosis.
Mitosis is a type of cell division in which parent cell is converted into two daughter cells having same number of chromosomes as that of the parent cell.
It is divided into the following stages-
1) Prophase- It is the first phase of mitosis in which condensation of chromosomes ( clearly visible chromosomes with sister chromatids) takes place and the nuclear membrane is disappeared.
2) Metaphase- It is the second phase in which chromosomes are aligned at the equatorial plate of the cell and they are anchored by microtubules from opposite poles.
3) Anaphase- It is the third phase in which each sister chromatid of the chromosome is pulled apart ( with the help of microtubules) towards the opposite pole.
4) Telophase- Chromosome decondensation takes place and nuclear membrane is formed so that two nuclei are visible now.
5) Cytokinesis- It is the last phase of mitosis in which division of cytoplasm takes place so that two daughter cells are produced having same number of chromosomes as their parent cell.
Search this on youtube : <span>Photosynthesis Equation Song - Biology Lesson
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haha this might help.
<span>AUTOTROPH 1. an organism that can make its own food
Plants like algae are autotrophs. They produce their own food with the use of light, carbon dioxide, water, and other chemicals that are vital in their food producing activity. Aside from plants, there are autotroph organisms. An example of this is phytoplanktons.
CALVIN CYCLE 2. the dark reaction process of photosynthesis that uses carbon dioxide for the synthesis of carbohydrates
The Calvin Cycle has three phases. These are 1) carbon fixation, 2) reduction reactions, and 3) RuBP regeneration.
This cycle occurs in the stroma of the chloroplast and it converts carbon dioxide and other chemical compounds into glucose.
CAROTENOID PIGMENT 3. a pigment ranging in color from yellow to red; helpful in capturing the Sun's light energy for use in photosynthesis
Carotenoid is a plant pigment. It produces yellow, orange, and red colors of many fruits and vegetables. Carotenoid pigment is identified as a class of phytonutrients that benefits human health. People who consumes carotenoid rich fruits and vegetables enjoys the antioxidant property of the food as well as the Vitamin A that some carotenoid convert into.
CHLOROPHYLL 4. a green pigment in plants that serves to trap the Sun's energy for photosynthesis
Chlorophyll is the combination of two Greek words "chloros" and "phyllon" which means green and leaf respectively. This pigment also contributes to human wellness as consumption of plants rich in chlorophyll are proven to be very healthy. These health benefits are 1) helps fight cancer, 2) improves liver detoxification, 3) speeds up the healing of wounds, 4) improves digestion and helps control weight, and 5) protects skin from skin virus like cold sores.
CHLOROPLAST 5. the tiny body that contains chlorophyll; part of the cell in which photosynthesis takes place
Chloroplast is a type of plastid that can be distinguished from other plastids due to its green color. Chloroplast is the only plastid that contains chlorophylls a and b, thus its green color.
PHOTOSYNTHESIS 6. a process that involves the use of carbon dioxide and water in the production of glucose and oxygen using the Sun's energy
RADIATION 7. transfer of heat or energy through rays of various wavelengths
</span><span>Radiation is defined as energy travelling through space. Sunshine or sunlight is an example of radiation. Its ultra violet rays radiates heat on the earths' surface which in turn helps our autotrophs undergo photosynthesis.
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