Photosynthesis and Photorespiration Quiz

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Questions and Answers

What is the main output of the Calvin cycle?

Oxygen

NADPH

ATP

Glucose (correct)

Which molecule does Rubisco add to RuBP during photorespiration?

Oxygen (correct)

Carbon dioxide

Glucose

NADPH

How many ATP molecules are consumed in the Calvin cycle to produce one glucose?

9 ATP

24 ATP

18 ATP (correct)

12 ATP

What is the consequence of photorespiration in plants?

It consumes oxygen without producing ATP. Signup and view all the answers

C4 plants have adapted to which of the following conditions?

Hot and dry Signup and view all the answers

What percentage of carbon fixed via the Calvin Cycle can be drained by photorespiration?

Up to 50% Signup and view all the answers

What is the primary function of the stomata in C4 and CAM plants?

Open at night to store CO2 Signup and view all the answers

How are gametes defined in terms of chromosome sets?

Haploid cells with one set of chromosomes Signup and view all the answers

What constitutes a somatic cell's chromosome set?

Two sets of chromosomes Signup and view all the answers

What determines the sex of an individual in humans?

The presence of Y chromosome Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

S phase Signup and view all the answers

Which of these phases is NOT part of the interphase?

M phase Signup and view all the answers

What role does the G2 checkpoint serve in the cell cycle?

It halts the cell cycle until conditions are favorable Signup and view all the answers

What type of chromosomes are homologous chromosomes?

Matching pairs with possible different alleles Signup and view all the answers

How many chromosomes are found in a typical human somatic cell?

46 chromosomes Signup and view all the answers

What is pleiotropy?

A gene that affects multiple traits. Signup and view all the answers

What defines polygenic inheritance?

A single trait determined by multiple genes. Signup and view all the answers

Which of the following best describes sex linkage?

Genes located on sex chromosomes, usually recessive. Signup and view all the answers

How does environmental influence affect human traits?

It can alter the expression of multiple traits. Signup and view all the answers

What does the term 'multiple alleles' refer to?

The presence of three or more alleles for a gene in a population. Signup and view all the answers

What is a characteristic of sex-influenced traits?

Their expression can differ in males and females. Signup and view all the answers

Why are recessive diseases expressed more frequently in males?

Males inherit only one X chromosome. Signup and view all the answers

What is linkage in genetics?

When genes on the same chromosome are inherited together. Signup and view all the answers

What is the main result of crossing over during meiosis?

Formation of recombinant chromosomes Signup and view all the answers

How does meiosis differ from mitosis regarding the genetic similarity of daughter cells?

Meiosis produces genetically diverse cells Signup and view all the answers

Which of the following statements about aneuploids is accurate?

They result from chromatid separation failure Signup and view all the answers

What typically causes mutations in an organism's DNA?

Errors during DNA replication Signup and view all the answers

Which process contributes to genetic variation by sorting paternal and maternal chromosomes independently?

Independent assortment Signup and view all the answers

Which of the following best describes the overall purpose of meiosis?

To form gametes with reduced chromosome numbers Signup and view all the answers

What role does the synaptonemal complex play during prophase I of meiosis?

Aligns homologous chromosomes Signup and view all the answers

Which of the following terms refers to the observable traits of an organism?

Phenotype Signup and view all the answers

Which event in meiosis helps to create genetic diversity?

Crossing over Signup and view all the answers

What is the average number of new mutations expected per generation in humans?

64 Signup and view all the answers

What characterizes necrosis in contrast to apoptosis?

Random fragmentation of cells and inflammation Signup and view all the answers

How do cancer cells differ in their requirements for growth factors?

They do not need growth factors to grow and divide Signup and view all the answers

What is the primary result of mitosis?

Formation of two identical daughter cells Signup and view all the answers

What occurs during prophase in mitosis?

Chromosomes condense and spindle fibers form Signup and view all the answers

What distinguishes meiosis from mitosis?

Meiosis results in four haploid cells Signup and view all the answers

What happens during anaphase in mitosis?

Sister chromatids separate and move to opposite poles Signup and view all the answers

What role do microtubules play during cell division?

They control chromosome movement Signup and view all the answers

What is a consequence of nondisjunction during meiosis?

It produces gametes with an abnormal number of chromosomes Signup and view all the answers

During which phase do homologous chromosomes separate?

Anaphase I of meiosis Signup and view all the answers

Which of the following correctly describes telophase?

Nuclear membranes re-form around each set of chromosomes Signup and view all the answers

What is a key difference between the end products of meiosis and mitosis?

Meiosis results in four haploid cells, while mitosis results in two diploid cells Signup and view all the answers

What happens during cytokinesis?

The cytoplasm divides, resulting in separate daughter cells Signup and view all the answers

Study Notes

Photosynthesis Phases

The Calvin cycle has three phases: Carbon fixation, Reduction, and Regeneration
The Carbon Fixation phase uses carbon dioxide to create a six-carbon compound: 3-phosphoglycerate, via RuBP (Ribulose bisphosphate )
The Reduction phase uses 6 NADPH and 6 ATP to produce 12 G3P (glyceraldehyde 3-phosphate).
The Regeneration phase uses 6 ATP to regenerate 6 RuBP molecules.
The Calvin cycle produces 1 Glucose, and uses 18 ATP and 12 NADPH.

Photorespiration

In the Calvin cycle, rubisco can add oxygen to RuBP.
Oxygenation of RuBP leads to Photorespiration, which consumes oxygen and organic sugars, and releases carbon dioxide, without making ATP or sugar.
This process occurs when plants cannot photosynthesize efficiently in hot, dry areas.
Photorespiration can drain up to 50% of a plant's carbon that was fixed via the Calvin cycle.

C4 and CAM Plants

C4 plants minimize photorespiration costs by converting CO2 into four-carbon compounds.
Examples of C4 plants: Sugarcane plants.
CAM plants store CO2 during the night and undergo the Calvin cycle during the day.
Examples of CAM plants: Pineapple plants.

The Human Genome

The human genome consists of 46 chromosomes, organized into 23 pairs.
Somatic cells (non-reproductive) are diploid (2n) containing two sets of chromosomes.
Gametes (reproductive cells) are haploid (n) containing a single set of chromosomes.
Sex chromosomes determine the sex of an individual: XX for females, XY for males.
The remaining 22 pairs of chromosomes are called autosomes.

The Cell Cycle

Interphase is the longest part of the cell cycle, and consists of three phases: G1, S, and G2.
In G1 phase, cells grow and bio-synthetic pathways resume.
In S phase, genetic information is duplicated.
In G2 phase, the cell prepares for mitosis.
M phase (mitotic phase) includes Mitosis and Cytokinesis.

Cell Death and Growth

Necrosis is a form of unintentional cell death, often caused by damage.
Apoptosis is a form of programmed cell death, eliminating unwanted cells.
Cancer cells are characterized by unchecked growth, ignoring normal cell growth regulators like anchorage dependence, density-dependent inhibition and growth factors.

Mitosis

Mitosis is the process by which replicated chromosomes are separated into two new nuclei.
It results in two daughter cells that are genetically identical to the parent cell.
Mitosis is crucial for development, growth, and repair in multicellular organisms.

Meiosis

Meiosis is the process by which homologous chromosomes are separated during Meiosis I and sister chromatids are separated during Meiosis II.
It results in four haploid (n) daughter cells, genetically different from the parent cell.
Meiosis is essential for sexual reproduction.

Crossing Over

Crossing over occurs during Prophase I of Meiosis.
Non-sister chromatids exchange genetic material, leading to the formation of recombinant chromosomes.
This process contributes to genetic variation by combining DNA from both parents.

Genetic Variation

Genetic variation refers to the differences in DNA sequences between individuals within a population.
Sources of genetic variation include:
- Crossing Over: Exchange of genetic material between homologous chromosomes.
- **Independent Assortment of Chromosomes`: Random segregation of homologous chromosomes during Meiosis I.
- Random Fertilization: Combination of genetically unique sperm and egg cells.
- Mutations: Changes in DNA sequences.

Mendel's Laws of Inheritance

Genotype: The genetic makeup of an organism.
Phenotype: The physical appearance or characteristics of an organism.
Allele: Alternative forms of a gene.
Dominant allele: Allele whose phenotype is expressed even when only one copy is present.
Recessive allele: Allele whose phenotype is only expressed when two copies are present.

Terms

Genetics: The study of heredity.
Heredity: The transmission of traits from one generation to the next.
Gregor Mendel: A scientist who studied inheritance patterns in pea plants, pioneering our understanding of genetics.

Pleiotropy and Polygenic Inheritance

Pleiotropy: One gene affects multiple traits. Example: Sickle cell anemia.
Polygenic Inheritance: Multiple genes contribute to a single trait. Example: Height, skin color.

Other Phenotype Affecters

Multiple Alleles: More than two alleles of a gene present within a population, like blood groups.
Environment: Environmental factors, such as diet, climate, or illness can influence an individual's phenotype.
Linkage: Genes located close together on a chromosome tend to be inherited together.

Sex Chromosomes

Sex Linkage: Genes located on sex chromosomes, often exhibiting different expression patterns between males and females. Example: Color blindness, hemophilia.
Sex-Influenced: Genes located on autosomes, but whose expression is influenced by sex. Example: Pattern baldness.

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Description

Test your knowledge on the phases of photosynthesis, including the Calvin cycle and the impact of photorespiration. This quiz covers the mechanisms of carbon fixation, reduction, and regeneration, as well as adaptations in C4 and CAM plants to minimize photorespiration effects.