Life Science NJ ASK Review 8 th Grade Science

What is a food chain? A food chain is “a sequence of organisms, each of which uses the next, lower member of the sequence as a food source 1 ”

Important facts about food chains In a food chain each organism obtains energy from the one at the level below. Plants are called because they create their own food through photosynthesis Animals are because they cannot create their own food, they must eat plants or other animals to get the energy that they need. producers consumers

Four types of consumer animals that eat only plants animals that eat only other animals. animals that eat animals and plants. Animals that eat dead materials and organic wastes Herbivores: Carnivores : Omnivores: Detritivores:

Other Ways to Classify Consumers 1.Primary Consumers: 2.Secondary Consumers: 3.Tertiary Consumers: Herbivores. Carnivores that eat herbivores. Carnivores that eat other carnivores; an animal that feeds only on secondary consumers.

Identify the producer, one primary consumer, one secondary consumer and a tertiary consumer. Producer Primary Consumers Secondary Consumers Tertiary Consumers

Which biome? …. has the greatest diversity? …least amount of precipitation? …located in northern altitudes? …has rich topsoil? (TWO) …has harsh winters? (TWO) Rainforest Desert Tundra Grassland and deciduous forests Tundra and Taiga

Interaction of Organisms Predator vs Prey – hunter vs hunted Symbiotic Relationships – Mutualism: both organisms benefit from the relationship Ex: zebra and oxpecker; rhino and birds, shark and cleaner fish; bee and flower – Parasitism: one organism benefits, one is harmed ex: ticks on animals; mistletoe – Commensalism: one species benefits and the other is neither harmed nor helped Ex: cockleburs; cattle and cattle egrets

Symbiotic Relationships

Animal vs. Plant Cell Determine the similarities and differences.

Animalvs. Plant Lysosomes Many small vacuoles Nucleus is usually in the center Rounded Mitochondria Ribosomes ER Rough Smooth Vacuoles Nucleus Nuclear Membrane Cell Membrane Cytoplasm Golgi Apparatus Chloroplasts Cell Walls One Large Central Vacuole Nucleus usually pushed to the side Usually rectangular(ish)

Hierarchy of Biological Classification 3 Domains, 6 Kingdoms Multicellular – living things made up of two or more cells Unicellular – living things that are made of only one cell Eukaryotic – contains membrane bound organelles such as the nucleus Prokaryotic – no membrane bound nucleus

Hierarchy of Biological Classification

An easy way to remember… King = Kingdom Philip = Phylum Came = Class Over = Order For = Family Good = Genus Soup = Species Which taxonomic group includes all the other groups? Human beings are most closely related to other animals that are in the same ________________. Kingdom Species

Organization of Living Organisms Cells -basic unit of an animal’s structure -become specialized _______________________________ Tissues -made of cells that work together to perform a specific function __________________________________________ Organs -made of different types of tissues that work together to perform a specific function ____________________________________________________ Organ Systems -made of organs that work together to perform a specific function _____________________________________________________________ Organisms

Genetics - What are traits? Physical Traits – Can be seen by others – Examples: Acquired Traits – Learned skills – Examples: Behavioral Traits – Instinctual actions – Examples: Eye color, hair color, height, left handed Playing a sport, riding a bike, playing a musical instrument Nest building and migration

Genetics Genotype Phenotype Allele An individual with non-identical alleles of a gene is for that gene – Examples: Bb, Tt, Aa An individual with identical alleles of a gene is for that gene – Examples: BB or bb, TT or tt The genotype is the specific genetic makeup of an individual, usually in the form of DNA. It codes for the phenotype of the individual. An individual’s observable traits. What people can SEE when they look at you Different forms of a gene, which produce variations of a genetically inherited trait. heterozygous homozygous

Terms Used in Modern Genetics An allele is dominant if its effect masks the effect of a recessive allele paired with it – Capital letters (A) signify dominant alleles; lowercase letters (a) signify recessive alleles – Homozygous dominant (AA) – Homozygous recessive (aa) – Heterozygous (Aa) A genetic factor that blocks another genetic factor is called A genetic factor that is blocked by the presence of a dominant factor is called recessive dominant

Generation 1 BB b b In this case we have a dad with black fur and a mother with white fur. Because black is the dominant gene, we write it with a capital ‘B’. White fur is a recessive trait. It is written with a lowercase ‘b’. It does not matter what letter we choose to represent a gene, but capital letter is always dominant and lowercase is always recessive.

Tongue Curling Tt T T Copy into your notebook and complete the Punnett’s Square. What percentage of offspring will be able to curl their tongue? T=can curl T=cannot curl

When Would a Cell Divide? Growth Repair or Replacement Different cells divide at different rates: Most mammalian cells = hours Some bacterial cells = minutes

Mitosis vs. Meiosis Mitosis – a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth. Meiosis – a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.