Unit 1 Review: Short Answer

Question 1

Name SIX characteristics that all living things share

Answer 1

1. Cells: All living things are composed of cells. Cells are very small, so large multicellular organisms contain many cells.
2. Organization: All living things are highly organized at both the molecular and cellular levels. specific cell structures carry out particular functions. In organisms, cells and groups of cells are organized by their function
3. Energy use: All living things use energy in a process called METABOLISM which is the sum of all the chemical processes that occur in the organism. Energy is needed to grow and reproduce etc.
4. Homeostasis: Or balance. All living things maintain stable internal conditions. Ex: a cell closely controls its water content by taking in or releasing water (osmosis)
5. Growth: All living things grow, as do many non living things. Non living things such as icicles or crystals grow by accumulating more of the material they are made of. Living things grow as a result of CELL DIVISION (mitosis) and cell enlargement
6. Reproduction: All species of organisms have the ability to reproduce. This may be sexually (two parents) or asexually (one parent).

Question 2

Why is reproduction an important characteristic of life? (Np 6)

Answer 2

All organisms need to produce new organisms like themselves in order to transmit hereditary information (in the form of DNA) to their offspring. If there is no reproduction the species will go extinct

Question 3

What is the difference between asexual and sexual reproduction? (notes, N p 6-7)

Answer 3

Sexual- hereditary info from 2 parts of a single organism, or from 2 organisms of the same species combined
Asexual- hereditary info from different organisms is not combined. 1 parent only.

Question 4

Compare heterotrophs with autotrophs. (N pp 382-383)

Answer 4

Autotroph: organism that obtains its energy from abiotic sources, such as sunlight or inorganic chemicals
autotrophs use photosynthesis to create their own food through photosynthesis (ex: plants)

Heterotroph: organism that obtains its energy and nutrients by consuming other organisms.
Heterotrophs - organisms that can’t make their own food (don’t photosynthesize), have to eat other organisms or their by-product to meet their energy needs. (ex: animals, fungi). They must consume autotrophs, or other heterotrophs for food (ex: cows, rabbits, humans)

Question 5

What would happen if all autotrophic organisms died, leaving only heterotrophic organisms? (Np 382)

Answer 5

The entire food chain would collapse- all heterotrophs would die bc their food source would be gone and they can’t make their own.

Question 6

Compare photosynthesis with cellular respiration (with regards to chemical reactions/equations and what types of organisms use each). (N p 109 &, see Figure 4.3) *Don’t forget to identify where each process occurs! (Np 383)

Answer 6

Photosynthesis: In the chloroplast. Creates energy using sunlight and organic compounds
6CO2 + 6H2O —> C6H12O6 + 6O2
(Makes oxygen)

Cellular respiration: Cellular respiration occurs in the mitochondria. and breaks down organic compounds to create energy.
C6H12O6 + 6O2 —> 6CO2 + 6H2O
(Produces H2O and CO2)

Question 7

Give several differences between prokaryotes and eukaryotes (N p 68)

Answer 7

Prokaryotic cells:
- Have no nucleus
- Have no membrane bound organelles
- Microscopic single celled organism
- Includes Kingdom Monera/Bacteria

Eukaryotic cells
- Have a nucleus
- Have other membrane bound organelles
- Multicellular or single celled organisms
- Include kingdom Plantae, Animalia, Fungi, Protista

Question 8

Define homeobox genes and give an example.

Answer 8

• Any of the developmental control genes that define the head-to tail pattern of development in animal embryos. (Homeotic genes control early development in animals)
- Any of the developmental control genes involved in establishing the anterior-posterior axis and the identity of each body segment in organisms, especially during early embryonic development. Mutation in this gene leads to the formation of a normal structure or organ in place of another at an abnormal site.

• The first hox gene was discovered in Drosophila (fruit flies.) Mutation in this gene leads to the formation of a normal structure or organ in place of another at an abnormal site. i.e. mutation in the antennapedia hox gene of Drosophila leads to the formation of a leg in place of an antenna from its head.

Question 9

Define epigenetics and briefly explain the 2 examples of this that we studied in class.

Answer 9

Epigenetics refers to the idea that environmental factors can change how a DNA sequence is expressed.
- Obesogens: compounds that can cause weight gain even if your parents or grandparents were exposed.
- Trauma from survivors of residential schools is passed down to other generations.

Question 10

What are obesogens? Explain THREE concerns scientists have about these chemicals.

Answer 10

Obesogens are compounds which cause weight gain
- They directly affect adipocytes (fat cells)
- They change metabolism
- It changes the way the body regulates hunger