1 What is a controlled experiment Controlled experiment

1. What is a controlled experiment? Controlled experiment– tests effect of a single variable while keeping all other variables the same

2. What is the difference between a hypothesis and a theory? hypothesis– a possible explanation to a scientific question. (an “educated guess” based on prior knowledge and observations) Theory– a well tested and supported hypothesis (Cell theory, theory of Natural Selection, Atomic theory)

Observation classified into two types: Quantitative– involve numbers, counting, measuring objects. Qualitative– involve characteristics that cannot be easily measured or counted such as color or texture

3. When conducting experiments, sometimes the results are not consistent and may yield results that are obviously wrong. What might be some typical sources of unavoidable errors? • Human error (mistakes in conducting experiment) • Small sample tested • Contaminated sample

4. Why is the cell membrane referred to as being semi-permeable? Most membranes are selectively permeable (some materials can pass across membrane and others cannot) like “sieve”

6. What is an enzyme and how does it speed up a chemical reaction? Enzymes– specialized proteins that act as biological catalysts (catalysts– a substance that speeds up rate of chemical reaction by lowering a reactions activation energy)

Enzymes are very specific Name of enzyme derived from reaction it catalyzes Enzymes are not used up in a chemical reaction.

7. What conditions affect the action of an enzyme (name three things) • Temperature • p. H • Presence of substrate

14. Proteins are all made from amino acids. What makes one protein different from another? The number of amino acids and the sequence of amino acids (like letters in an alphabet spelling different words)

15. What effect does temperature have on proteins? It changes the 3 -dimensional structure of the protein (this will also change the way the protein functions) Like when you cook a steak or eggs- it changes the consistency. It may also stop the action of an enzyme- snake venom

17. What is mitosis and what types of cells undergo mitosis? Division of cells forming two identical new daughter cells (body cells) 2 n → 2 n Part of Cell Cycle PMAT (stages) followed by cytokinesis

18. What is the difference between diploid cells and haploid cells? Diploid (2 n)- two sets of chromosomes (normal number in body cells) Haploid (n)- half the number of chromosomes (found in sex cells-gametes)

19. What process produces diploid cells and which produces haploid cells? Mitosis- makes diploid cells 2 n → 2 n Meiosis- makes haploid sex cells (gametes) 2 n → n + n

20. What is meiosis and what does it result in? Process of producing sex cells (gametes) Results in four haploid (n) cells (sperm or egg)

21. Explain why this is a good representation of fertilization: n + n =2 n Shows two haploid cells (gametes) coming together to produce diploid (2 n) cell-zygote n + n =2 n

22. What is meant be segregation when sex cells (gametes) are produced?

22. What is meant be segregation when sex cells (gametes) are produced? Chromosomes segregate (separate) during meiosis.

23. What is independent assortment? Each of the chromosome pairs separate independently of the others (like flipping a coin each time to determine which one to use)

24. What is a mutation? Any change in an organisms DNA. Happens naturally and randomly

25. Mutations may or may not affect the expression of a gene. Why? • It may not change the amino acid it codes for (there are multiple combinations that code for same amino acid) • It may be a mutation in area of DNA that does not code for proteins

26. What are sex chromosomes and what combinations would result in a boy or a girl? Girl = XX Boy = XY 23 rd pair of chromosomes in humans