Biology 2024 with corrections

What are all living things made of?

Cells

Name the key organelles in an animal or plant cell.

Cell membrane, cell wall, cytoplasm, mitochondria, chloroplast, endoplasmic reticulum, Golgi body, vacuole, ribosome, centriole, nucleus, nuclear membrane

What is the function of the cell membrane?

Controls the movement of substances in and out of the cell

What is the function of the cell wall?

Provides structure and protection; found only in plant cells

What is the function of cytoplasm?

Jelly-like substance that holds organelles in place and allows chemical reactions to occur

What is the function of mitochondria?

Produces energy (ATP) for the cell through cellular respiration

What is the function of chloroplast?

Conducts photosynthesis to produce energy for plant cells

What is the function of the endoplasmic reticulum?

Transports proteins and other materials within the cell; can be rough (with ribosomes) or smooth (without ribosomes)

What is the function of the Golgi body?

Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell

What is the function of the vacuole?

Stores nutrients, waste products, and other materials; large central vacuole is found in plant cells

What is the function of ribosomes?

Synthesizes proteins

What is the function of the centriole?

Assists with cell division in animal cells

What is the function of the nucleus?

Stores the cell’s genetic material (DNA) and controls cell activities

What is the function of the nuclear membrane?

Protects the nucleus and controls movement of materials in and out of it

What is one main difference in structure between plant and animal cells?

Plant cells have a cell wall and chloroplasts, animal cells do not

What is DNA?

The molecule that contains genetic information for the development, function, and reproduction of all living organisms

Describe the structure of DNA.

DNA is a double helix structure composed of two strands of nucleotides twisted around each other

What is a nucleotide?

The basic building block of DNA, consisting of a sugar, phosphate, and nitrogen base

What are the four nitrogen bases in DNA?

Adenine, thymine, cytosine, guanine

Which nitrogen bases pair together in DNA?

Adenine pairs with thymine, cytosine pairs with guanine

What is complementary base pairing?

The concept that in DNA, adenine always pairs with thymine and cytosine always pairs with guanine

Who discovered the double helix structure of DNA?

James Watson and Francis Crick and Rosalind Franklin

Why are James Watson and Francis Crick significant in biology?

They developed the double helix model for the structure of DNA

What is a gene?

A segment of DNA that codes for a specific protein or trait

What is the basic purpose of protein synthesis?

To create proteins that are essential for cellular structure and function

What is DNA replication?

The process by which DNA makes an identical copy of itself before cell division

Which enzyme unwinds the DNA double helix during replication?

DNA helicase

Which enzyme builds the new DNA strand by adding nucleotides during replication?

DNA polymerase

What is a chromosome?

A structure composed of DNA and proteins that contains genetic information

What is a chromatid?

Each of the two identical halves of a chromosome

What is a centromere?

The region where two chromatids are joined together in a chromosome

What is mitosis?

The process of cell division that produces two identical diploid daughter cells

What is the purpose of mitosis?

To allow growth, tissue repair, and asexual reproduction in organisms

Where does mitosis occur?

In somatic (body) cells

List the stages of mitosis in order.

Prophase, metaphase, anaphase, telophase

Describe what happens in prophase.

Chromosomes condense, the nuclear membrane dissolves, spindle fibers form

Describe what happens in metaphase.

Chromosomes line up at the cell’s equator

Describe what happens in anaphase.

Sister chromatids are pulled apart to opposite poles of the cell

Describe what happens in telophase.

Nuclear membranes form around each set of chromosomes, and the cell begins to divide

What is the difference between haploid and diploid cells?

Haploid cells have one set of chromosomes, diploid cells have two sets of chromosomes

What are homologous chromosomes?

Chromosome pairs, one from each parent, that are similar in shape, size, and genetic content

What is meiosis?

The process of cell division that produces four non-identical haploid daughter cells (gametes)

What is the purpose of meiosis?

To produce gametes for sexual reproduction

Where does meiosis occur?

In the gonads (ovaries and testes)

Who is Gregor Mendel?

A scientist known as the “Father of Genetics” for his study of inheritance in pea plants

How is genetic information passed from parents to offspring?

Through the processes of meiosis and fertilization

What is the difference between a gene and an allele?

A gene is a segment of DNA that codes for a trait, an allele is a variation of that gene

What is a dominant trait?

A trait that is expressed when at least one dominant allele is present

What is a recessive trait?

A trait that is expressed only when two recessive alleles are present

What is genotype?

The genetic makeup of an organism (the combination of alleles)

What is phenotype?

The observable characteristics of an organism

What does homozygous mean?

Having two identical alleles for a particular gene

What does heterozygous mean?

Having two different alleles for a particular gene

What is a Punnett square?

A tool used to predict the possible genotypes and phenotypes of offspring in genetic crosses

How is sex determined in humans?

By the combination of sex chromosomes (XX for female, XY for male)

What is a karyotype?

A visual representation of all the chromosomes in a cell, arranged in pairs

How can you distinguish between a male and female karyotype?

Female karyotype has XX chromosomes, male karyotype has XY chromosomes

What are autosomes?

Chromosomes that are not involved in sex determination

What are sex chromosomes?

Chromosomes that determine the sex of an organism (X and Y chromosomes)

What is the theory of evolution by natural selection?

A theory that explains how species evolve and adapt over time based on inherited traits that aid survival and reproduction

Define species.

A group of organisms capable of interbreeding and producing fertile offspring

Define variation.

Differences in physical traits among individuals in a population

What is the difference between gene mutations and chromosomal mutations?

Gene mutations affect a single gene, chromosomal mutations affect the structure or number of chromosomes

What is a mutagen?

An agent that causes mutations in DNA

Define population.

A group of individuals of the same species living in a specific area

Define gene pool.

The total collection of alleles in a population

What is allele frequency?

The relative frequency of an allele in a population’s gene pool

What factors can change allele frequencies in a gene pool?

Mutations, migration (gene flow), and environmental pressures

Define evolution.

A change in the genetic composition of a population over successive generations

What is natural selection?

The process where organisms better adapted to their environment tend to survive and produce more offspring

What is speciation?

The formation of new and distinct species in the course of evolution

How does speciation occur?

Through variation, struggle for existence, isolation, and differential selection within gene pools

How do fossils support the theory of evolution?

Fossils provide evidence of organisms that lived in the past and show changes over time

How do comparative studies in anatomy, embryology, DNA, and proteins support evolution?

They reveal similarities that suggest common ancestry among different species

If a homozygous dominant (AA) parent is crossed with a homozygous recessive (aa) parent, what are the possible genotypes of the offspring?

All offspring will be heterozygous (Aa)

If a heterozygous (Aa) parent is crossed with a homozygous recessive (aa) parent, what percentage of the offspring will have the recessive phenotype?

50% will have the recessive phenotype (aa)

If two heterozygous parents (Aa) are crossed, what are the possible genotypes of the offspring?

AA, Aa, Aa, aa

In a cross between two heterozygous parents (Aa x Aa), what percentage of the offspring will have the dominant phenotype?

75% will have the dominant phenotype (AA or Aa)

In a monohybrid cross between two heterozygous parents (Aa x Aa), what is the ratio of genotypes in the offspring?

1 AA : 2 Aa : 1 aa

If a homozygous dominant (BB) parent is crossed with a heterozygous (Bb) parent, what are the possible genotypes and their ratios in the offspring?

50% BB, 50% Bb

If a trait is dominant and represented by the allele “D,” what is the phenotype of an individual with genotype Dd?

The individual will display the dominant phenotype

In a cross between a heterozygous (Bb) and a homozygous recessive (bb) individual, what percentage of the offspring will be heterozygous?

50% of the offspring will be heterozygous (Bb)

In a Punnett square where both parents are homozygous recessive (bb x bb), what will the genotype and phenotype of all offspring be?

All offspring will be bb and will display the recessive phenotype