living world

DNA

A molecule that carries genetic instructions used in growth, development, functioning, and reproduction of all living organisms.

Chromosome

A long, thread-like structure made of DNA and proteins that contains genes, located in the nucleus of eukaryotic cells.

Gene

A segment of DNA that contains instructions for making a specific protein or set of proteins, ultimately determining traits.

Allele

For the gene that determines flower color in pea plants, there are alleles for purple (dominant) and white (recessive). The presence of one or two purple alleles results in purple flowers, while two white alleles result in white flowers.

Trait

A specific characteristic or feature of an organism, such as eye color, height, or the ability to roll one's tongue.

Inherited

The process by which genetic information is passed from parents to offspring through genes.

Diploid Cell

A cell that contains two complete sets of chromosomes, one from each parent, totaling 46 chromosomes in humans.

Haploid Cell

A cell that contains one complete set of chromosomes, having 23 chromosomes in humans.

Meiosis

A type of cell division that reduces the chromosome number by half, producing four haploid cells, essential for sexual reproduction.

Mitosis

A type of cell division that results in two identical diploid cells, maintaining the same chromosome number as the original cell.

Fertilisation

The process in which a sperm cell and an egg cell unite to form a zygote.

Gamete

A haploid reproductive cell (sperm or egg) that carries genetic information.

Zygote

The fertilized egg that results from the union of sperm and egg, which develops into an embryo.

Embryo

An early stage of development in multicellular organisms, starting from the zygote.

What is DNA and why is it relevant to human beings?

is the hereditary material in humans, containing the genetic blueprint guiding development, functioning, and reproduction.

How many chromosomes do humans have?

Humans have 46 chromosomes, organized into 23 pairs.

What is a homologous pair?

A homologous pair consists of two chromosomes that have the same structure and carry the same types of genes.

How do inherited traits work?

Inherited traits are determined by genes on chromosomes; gametes carry alleles which combine at fertilization.

Describe Mitosis.

Mitosis results in two genetically identical diploid daughter cells through several phases including prophase, metaphase, anaphase, and telophase.

Describe Meiosis.

Meiosis involves two rounds of division resulting in four haploid cells, introducing genetic diversity and reducing chromosome number.

Mitosis phases

The key phases of mitosis are prophase, metaphase, anaphase, and telophase.

Purpose of Mitosis

Mitosis is crucial for growth, tissue repair, and asexual reproduction.

Purpose of Meiosis

Meiosis is essential for reducing chromosome number and ensuring genetic diversity in gametes.

What does a gamete carry?

A gamete carries genetic information as a haploid reproductive cell.

What is a diploid number?

The diploid number is the total number of chromosomes in a somatic cell, which is 46 in humans.

What is crossing over?

Crossing over is the exchange of genetic material between homologous chromosomes during meiosis.

What is the result of fertilization?

Fertilization results in the formation of a zygote.

How is genetic variation introduced?

Genetic variation is introduced during meiosis through crossing over and independent assortment.

Difference between haploid and diploid cells

Haploid cells have one set of chromosomes while diploid cells have two sets.

What role do alleles play?

Alleles contribute to variations in traits by being different versions of a gene.

What is the significance of traits?

Traits are specific characteristics of an organism that can be inherited.

What is an embryo's developmental stage?

An embryo is the early stage of development following the zygote.

How does DNA structure contribute to its function?

The double helix structure of DNA allows for accurate replication and storage of genetic information.

state the purpose of respiration

The purpose of respiration is to produce energy in the form of ATP by converting glucose and oxygen, while also removing carbon dioxide, maintaining pH balance, and supporting essential cellular processes.

describe where respiration takes place in the body

Respiration primarily takes place in the mitochondria of cells, where aerobic respiration occurs. Additionally, the process of gas exchange (oxygen intake and carbon dioxide removal) occurs in the lungs, specifically in the alveoli.

name two substances needed for respiration

glucose and oxygen

name a substance the body needs to get rid of from repiration

The body needs to get rid of carbon dioxide (CO₂) produced during respiration.

heterozygous homozygous dominant and homozygous recessive

• Heterozygous: An organism with two different alleles for a particular gene (e.g., Aa).

• Homozygous Dominant: An organism with two identical dominant alleles for a gene (e.g., AA).

• Homozygous Recessive: An organism with two identical recessive alleles for a gene (e.g., aa).

the main function of the diaphram

suck air into the lungs

gas exchange

is the diffusion of gases into and out of cells

Diffusion

arteries

carry bloods from the heart. have thick muscle walls, so that blood is transported under pressure(will flow to all cells)

veins

are blood vessels that carry deoxygenated blood back to the heart. They have thinner walls and often contain valves to prevent back flow

capilleries

are found everywhere in the body. their walls are one cell thick, so gases and nutrients diffuse across them easily

circulatory system

The circulatory system consists of the heart, blood vessels, and blood, transporting oxygen, nutrients, and waste throughout the body. The heart pumps oxygen-rich blood to tissues and returns oxygen-poor blood to the lungs, essential for maintaining health and homeostasis

alveoli

Alveoli are tiny air sacs in the lungs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be removed.

blood flow

as it pumps blood to the lungs and the body simultaneously. blood goes to the lungs to become oxygentated it is transported around the body

name 2 types of human sex cells

woman (xx) male (xy)

give an example of an acquired trait

ability to speak a language.

how do we inherit feature from our family

We inherit features from our family through genes from our parents

each human sex cell contains

23 chromosomes

define phenotype

Phenotype refers to the observable traits or characteristics of an organism, such as physical appearance, behavior, and physiological features

what molecule holds an organisms genetic information

DNA

deoxygenated blood

leaves the right ventrical of the heart via the pulmonary artery and travels to the lungs, where gas exchange occurs. blood then returns as oxygenated blood to the left atrium of the heart via the pulmonary vein

oxygenated blood

leaves the left ventricle via the aorta, and from there it flows through arteries to capillaries where it supplies the bodys many tissues with oxygen and removes excess carbon dioxide. deoxygentaed blood then returns via veins to the vena cava, re-enering the hearts right atrium